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Page 3 of 5 12‐ In the figure given below, Houston PC (PC‐HOU1) sends a packet to Dallas PC (PC‐DA1). The packet carries an ICMP Echo Request message which is 1400 Bytes long. The packet has a TTL setting of 5 hops. What happens to the packet as it travels from PC‐HOU1 to PC‐DA1? a) The packet will be fragmented and fragmented packets will arrive at PC‐DA1 individually. b) TTL of the packet will reach to 0 at PC‐DA1 it will be discarded c) Dallas router discards the packet and it will send PC‐HOU1 and ICMP “time exceeded” message. d) TTL value of the packet will be incremented by 1 at every router on the path. e) None of the above is true 13‐ A host computer “ X” with IP address 200.200.200.146/28 can’t seem to be able ping a host Y with IP address 200.200.200.160/28 . What is the reason? a) Address of computer Y is a broadcast address b) Address of computer Y is a subnet address c) Address of computer X is a subnet address d) Address of computer X is a broadcast address e) None of the above is the reason. 14‐ Assume that in the following figure both routers are configured correctly but no static routes are entered into those routers yet. If PC1 performs a Ping operation to PC0, what will happen? (a) Austin router will send a “Destination Unreachable” message to PC1 (b) Austin router will throw away the Ping packet and does nothing else (c) Houston router will send a “Destination Unreachable” message to PC1 (d) Hub0 will throw away the packet (e) None of the above is true 15‐ In the network shown below, Austin Ethernet LAN has the subnet address 172.16.100.0/25, the serial Link has the subnet address 172.16.0.0/25 and Houston Ethernet LAN has the subnet address 172.16.100.128/25. Austin and Houston routers’ Ethernet interfaces are assigned the last usable IP addresses in their subnets. On the serial link, Austin serial interface is assigned the first usable IP address and Houston serial interface is assigned the last usable IP address. Which of the following statements are true about the Default Gateway (DGW) IP addresses a) PC1 DGW: 172.16.100.254, PC0 DGW: 172.16.100.254 b) PC1 DGW: 172.16.100.126, PC0 DGW: 172.16.100.254 c) PC1 DGW: 172.16.100.254, PC0 DGW: 172.16.0.254 d) PC1 DGW: 172.16.0.254, PC0 DGW: 172.16.100.254 e) None of the above is correct

Page 1 of 6 3/10/2023 FCN MIDTERM TEST Special Code: 000001 75 Minutes LAST NAME______________________ FIRST NAME____________________________ You will assume that all 0 and all 1 subnets are USABLE unless otherwise stated. 1- An organization uses a Class-A address with a subnet mask of 255.255.128.0. How many subnets will be available in this organization? (a) 2 9 (b) 2 17 (c) 2 17 – 2 (d) 2 9 – 2 (e) None of the above 2- In the network given below, assume that PC1 and PC3 has the same Ethernet address (assume possible). What kind of problem does this pose in the operation of the shown network? (a) It will create an issue when an ARP request is sent on PC1’s network (b) There will be no problem in the operation of the network. (c) It will create an issue when an ARP request is sent on PC3’s network. (d) Both (a) and (c) above are true (e) None of the above is true 3- Which of the following is NOT a legitimate IP address to assign to a host? (a) 192.168.255.254/24 (b) 10.255.255.254/8 (c) 191.191.191.191/24 (d) 172.16.254.0/25 (e) All of the above are legitimate IP addresses 4- A broadcast Ethernet frame has its “ Type ” field value is set to hexadecimal value “ x0806 ”. What kind of payload would this frame be carrying? (a) It is carrying an IP broadcast packet (b) It is carrying an ARP response message (c) It is carrying an ICMP destination unreachable message (d) It is carrying a “IP Unicast” packet (e) None of the above 5- In which one of the following cases there is NO subnetting ? (a) IP address = 10.10.10.10 subnet mask = 255.255.0.0 (b) IP address = 191.168.169.170 subnet mask = 255.255.255.0 (c) IP address = 172.22.190.189 subnet mask = 255.255.255.0 (d) IP address = 192.168.0.0, subnet mask = 255.255.255.128 (e) In all of the above cases there is subnetting

Page 4 of 6 15- Which of the following operations must be performed first when an Ethernet card receives a broadcast Ethernet frame? (a) Destination MAC address in the Ethernet frame must be checked to make sure ffff.ffff.ffff (b) CRC field must be examined to detect errors (c) Source MAC address in the Ethernet frame must be checked to make sure ffff.ffff.ffff (d) Type field must be check to make sure it is 0800 hexadecimal (e) None of the above is correct 16- In an IP packet, the source IP address appears as “ c0 a8 b2 b2” in hexadecimal with subnet mask /28 (in decimal). What is the AHID number of this host? (a) AHID number is 2 (b) AHID number is 50 (c) AHID number is 18 (d) AHID number is 78 (e) None of the above 17- Two computers, PC1 and PC2 are on the same coaxial Ethernet LAN. Both PCs attempt to access the LAN at the same time and they collide. Later, they both PCs try and collide for the second time again. On the third attempt, as part of exponential binary back-off algorithm, each PC picks a random number which defines the amount of time slots to be waited. Which of the following will be true about this random number the PCs pick? a) It will be a number between 1 and 4 b) It will be a number between 1 and 8 c) It will be a number between 1 and 2 d) It will be a number between 1 and 16 e) It will be a number between 1 and 3 18- A computer with IP address 192.168.111.222/28 wants to send a packet to another computer with IP address 192.168.111.205. What should it do? (a) the destination computer is on the same subnet and it should send directly (b) the destination computer is on a different subnet and it should send via the default gateway (c) the destination computer address is not a legitimate address because it represents a subnet address (d) the destination computer address is not a legitimate address because it represents a broadcast address 19- In a subnet the broadcast IP address is given as 192.168.10.191/29. What is the subnet IP address for this particular subnet? a) 192.168.10.184 b) 192.168.10.176 c) 192.168.10.180 d) 192.168.10.160 e) None of the above 20- Ethernet card of a computer has the MAC address as a01b.9c38.0000 (in hexadecimal). For the given MAC address, what would be the IP address for this computer? (a) 160.27.156.56 (b) 156.56.208.177 (c) 27.156.56.208 (d) IP address can’t be determined from MAC address 21- What is the purpose of “ Listen Before Talking (LBT)” part of Ethernet medium access method? a) To detect potential collisions b) To sense idleness of the communications medium c) To avoid potential reflections from cable ends d) To reduce the effect of errors resulting from CRC field. e) None of the above

Page 1 of 5 Exercise Set 28 Answers are shown in red colors You will assume that all 0 and all 1 subnets are USABLE unless otherwise stated Each question is 4 points. 1- IP header length field in an IP packet is 4 bits long. This means that the largest possible IP header length is the following: a) 20 Bytes b) 30 Bytes c) 40 Bytes d) 60 Bytes e) None of the above 2- In wireless LANs MTU is 2304. If a PC is using Wireless LAN card at the link layer, what will be the maximum possible IP packet payload size in Bytes assuming typical packet header size? a) 2304 b) 1480 c) 2284 d) 2204 e) None of the above . 3- Which one of the following is NOT a broadcast address? (a) IP address = 129.7.191.255, subnet mask = 255.255.224.0 (b) IP address = 129.7.254.255, subnet mask = 255.255.254.0 (c) IP address = 129.7.207.255, subnet mask = 255.255.240.0 (d) IP address = 129.7.192.255, subnet mask = 255.255.255.0 (e) All of the above are broadcast addresses 4- A small company has acquired 192.168.222.0/24 Class C IP address to accommodate its four locations and its serial links to interconnect those locations. The company uses VLSM method for its subnets. The four locations are the following: Houston (headquarters), Dallas, Austin and El Paso. The company has 95 hosts in Houston, 47 hosts in Dallas, 23 hosts in Austin and 10 hosts in El Paso. Based on the given information, how many serial links (i.e. leased line links) would be possible after all address allocations for the four cities? Remember that in VLSM serial links use /30 subnet mask. a) 16 serial links are possible b) 12 serial links are possible c) 8 serial links are possible d) 4 serial links are possible e) None of the above is true 5- The IP address 199.199.199.183 has the AHID value “23”. Which of the following choices would be the correct subnet mask for this IP? (a) /25 (b) /26 (c) /27 (d) /28 (e) /29

Page 4 of 5 18- Assume that University of Houston system consists of four (4) campuses: Main , Victoria , Clear Lake and Downtown . Furthermore, assume that UH system has the Class B address 172.26.0.0/16. Also, assume that the host counts for Main, Victoria, Clear Lake and Downtown campuses are: 28,000 hosts, 12,500 hosts , 6,900 hosts and 3,300 hosts respectively. The given class B address space needs to be used by four campuses using VLSM design. Furthermore, assume that Main campus has 14 building s with all equal size host counts i.e all subnets are the same size meaning FLSM design in main campus). Based on the given information, what would be the subnet mask that should be used in Main Campus subnets (i.e. buildings)? a) /21 b) /20 c) /22 d) /23 e) None of the above is true 19- Which one of the following field contents change as an IP packet travels across a network of many routers? (a) Version Field (b) Source IP field (c) Header Length Field (d) TTL Field (e) All of the above field values remain intact as the packet travels 20- An IP packet carries 20 Bytes in its “ Options ” field. What would be the “Header Length” field setting of this packet in binary? a) 1010 b) 00101100 c) 00011000 d) 0101 e) None of the above is true 21- Which of the following is wrong about Ethernet frame format? (a) Ethernet headers are 18 Bytes long (b) Ethernet Type filed indicates what kind of payload is carried (c) CRC field is also known as FCS field (d) Ethernet Payload size can be at most 1500 Bytes (e) Ethernet addresses of Ethernet cards are unique by the design of the address structure 22- The following hexadecimal number sequence is the first 45 Bytes of an Ethernet frame that is carrying an IP packet and TCP segment as its payloads. What is the value of the first Byte in the TCP header (i.e. the first Byte after IP header) in hexadecimal format? ff ff ff ff ff ff 4b 2c 3c 1f 3d b7 08 00 46 00 01 4f f2 3d 00 00 16 06 89 39 c0 a8 7b 46 c0 a8 7b 5f 71 ce 3d fa 27 3b 56 d2 e5 67 32………… a) 71 b) Ce c) 3b d) 27 e) None of the above

Page 2 of 6 4- An organization is assigned the Class C IP address 200.201.202.0/24. This organization is using FLSM subnetting. It has its headquarters in Clear Lake and it has 9 additional branch locations. The headquarters is assigned the first (i.e. smallest value) usable subnet ID. The next subnet ID is assigned to first branch location, the next to second branch location etc. What is the broadcast address of the third branch location ? Assume that old style routers are used in this network. a) 200.201.202.79 b) 200.201.202.47 c) 200.201.202.63 d) 200.201.202.95 e) None of the above 5- The hexadecimal number sequence shown below is the first 40 Bytes of an Ethernet frame . Determine what kind of network or transport layer payload this frame is carrying. 0d 2c 3a 05 f2 fa 4b 2c 3c 1f 3d b7 08 06 47 00 01 4f f2 3d 00 00 08 06 2c 39 c0 a8 22 46 c0 a8 22 55 71 ce 3d fa 27 . . . . . . . . . . . . . . a) It is carrying an IP packet b) It is carrying an ICMP echo request message c) It is carrying an ICMP echo response message d) It is carrying an ARP request e) It is carrying an ARP response 6- Which one of the following CAN be used as a mask as host IP address 136.74.143.255? (a) /23 (b) /22 (c) /21 (d) /20 (e) None of the above can be used as mask 7- An organization uses a Class-A IP address with an FLSM subnet mask of 255.255.192.0. How many hosts will be available in each subnet of this organization? .a) 2 10 b) 2 12 c) 2 10 – 2 d) 2 14 – 2 e) None of the given choices is correct 8- What is the subnet address for the IP address (in hex form) b2 1c 9a d7 with subnet mask 255.255.248.0? .a) 178.28.152.0 b) 178.28.144.0 c) 178.28.154.0 d) 178.28.160.0 e) None of the given choices is correct 9- In the network shown below, Austin Ethernet LAN has the subnet address 180.181.100.0/25, the serial Link has the subnet address 180.181.0.0/25 and Houston Ethernet LAN has the subnet address 180.181.100.128/25. Austin and Houston routers’ Ethernet interfaces are assigned the last usable IP addresses in their subnets. On the serial link, Austin serial interface is assigned the first usable IP address and Houston serial interface is assigned the last usable IP address. Which of the following statements are true about the Default Gateway (DGW) IP addresses a) PC1 DGW: 180.181.100.254, PC0 DGW: 180.181.100.254 b) PC1 DGW: 180.181.100.254, PC0 DGW: 180.181.0.254 c) PC1 DGW: 180.181.100.126, PC0 DGW: 180.181.100.254 d) PC1 DGW: 180.181.0.254, PC0 DGW: 180.181.100.254 e) None of the above is correct

Page 5 of 6 20- You are given the IP address 191.191.0.0/16. You are asked to connect a total of 31 offices in Texas including Houston, Dallas, Austin, Brownsville, El Paso, Corpus Christi and 25 more cities. Assume that all 0 and all 1 subnets are NOT usable (i.e. you are using old style routers) . You use the optimal mask for this purpose (use same mask for all cities). You assign the first available subnet ID to Houston, next one to Dallas, next to Austin, next to Brownsville, next to El Paso, next to Corpus Christi and so on. What would be El Paso broadcast address? (a) 191.191.27.255 (b) 191.191.19.255 (c) 191.191.255.255 (d) 191.191.31.255 (e) none of the above 21- In an IP packet, the header length field has the following binary value: 0110. Is there “ options ” field in this packet header? (a) Yes, there is “options” field. (b) No, there is no “options” field. (c) “Options” field does not depend on the packet header size. (d) “Options” field exist if the packet header field has the value 0101. (e) None of the above is true 22- An organization has the Class B IP address 172.28.0.0/16. This organization needs subnets for its 28 locations in USA using FLSM. What is the maximum number of usable addresses that each location can have? (a) 4096 (b) 2048 (c) 1024 (d) 1022 (e) 2046 23- Which one of the following does NOT have the same meaning as “Ethernet Address”? .a) MAC address b) NIC Address c) Physical Address d) Hardware Address e) Global Address 24- In the network given below assume that PCB sends a packet to PCC What is the destination IP address in this packet and what is the destination MAC address of the frame that encapsulates this packet? (a) 192.168.3.10, ac.ab.aa.a9.a8.a7 (b) 192.168.3.1, a6.a5.a4.a3.a2.a1 (c) 192.168.1.1, a6.a5.a4.a3.a2.a1 (d) 192.168.3.10, a5.a6.a7.a8.a9.aa (e) None of the above MAC Addresses: PCA: a1a2.a3.a4.a5.a6 PCB: a0.a2.a4.a6.a8.aa Houston E0: a6.a5.a4.a3.a2.a1 Dallas E0: a5.a6.a7.a8.a9.aa PCC: ac.ab.aa.a9.a8.a7

Page 6 of 6 25- The hexadecimal number sequence shown below is the first 42 Bytes of an Ethernet frame which is carrying an IP packet as its payload. This frame is sent from a source computer which is using /28 as the subnet mask . Using the packet header format shown below, determine if the source and the destination computers are on the same subnet or on the same network. eb 2c 3a 05 f2 fa 4b 2c 3c 1f 3d b7 08 00 47 00 01 4f f2 3d 00 00 08 06 2c 39 c0 a8 67 46 c0 a8 76 55 71 ce 3d fa 27 3b 56 d2 . . . . . . . . . . . . . . a) Source and destination computers are on the same network but on different subnets b) Source and destination computers are on different Class C networks c) Source and destination computers are on the same network and on the same subnet d) Source and destination computers are on different Class B networks e) None of the above is true 26- Two PCs, PC-A and PC-B are interconnected with a long communication cable. PC-A sends to PC-B 8 data bits appended with a parity bit as shown in the figure below. Due to electrical noise shown in the figure, four of the bit values change during the transmission. What would PC-B do when it receives the shown 9-bit message? a) PC-B, using the parity bit concludes that there is no error in the received message and accepts the message b) PC-B, with the help of parity bit, decides that there is an error in the message and discards the message c) Parity bit allows PC-B to correct the errors in the message and PC-B accepts the corrected message d) PC-B cannot decide whether there is error or not and waits PC-A to send the message again e) None of the above is true 27- An IP packet has the binary value 00100001 in the “ Upper Layer Protocol ” field (which is also called “ Protocol ” field). What kind of payload is this packet carrying? a) ICMP b) UDP c) TCP d) ARP e) None of the above

1 EXERCISE SET 1 Assume that all 0 and all 1 subnets are NOT usable unless otherwise stated!!! 1- Which of the following is wrong about subnetting (a) Subnetting is used to create multiple subnets from one network address (b) Subnet mask determines what part of the host id to be used as subnet bits (c) In subnetting all “0” and all “1” are reserved numbers (d) Subnetting is only used with class C and class B addresses. (e) If no subnetting is used, host id and actual host id are the same 2- Which of the following is wrong about LANs and WANs (a) LANs cover small areas (b) Historically WANs precede LANs (c) WANs are built using shared links (d) Ethernet is a type of LAN (e) First operational WAN was funded by DoD. 3- Which of the following statements about networks and subnets is wrong (a) A Calss C address with mask 255.255.255.224 allows up to 6 subnets. (b) 192.168.255.5 is not an legitimate address because “255” is a reserved number. (c) All Class A addresses have 1 byte of Network ID and 3 bytes of Host ID (d) A Class C address with mask 255.255.255.0 implies that subnetting is not used (e) All Class C addresses start with a number between 192 and 223 4- What is the maximum number of hosts that can be used in a class B network with a subnet mask 255.255.254.0? (a) 510 (b) 511 (c) 1022 (d) 509 (e) 1023 5- What is the maximum subnets that can be used in a class C network with a subnet mask 255.255.255.224? (a) 14 (b) 16 (c) 30 (d) 32 (e) 6 6- Which of the following is wrong about packets in a TCP/IP network (a) All packets must have a source address and a destination address (b) Packet header is typically 20 bytes long (c) At every router, packet and segment headers are examined (d) Packets may make multiple “hops” before they can reach to the destination computer (e) Packets may be lost on the way for variety of reasons 7- Which of the following is a not in IP header? (a) TTL (b) CRC (c) ULP (d) Version (e) TOS

2 8- Which of the following statements is wrong about Ethernet (a) Ethernet is one of the most popular LANs (b) Ethernet LANs use 6-byte source and destination addresses (c) Ethernet allows to build subnets using subnet masks (d) Ethernet uses a random access mechanism (e) Ethernet allows sharing of the communication medium 9- Which of the following statements is wrong about class A, B and C addresses (a) Class A addresses allow largest number of hosts (b) Class C addresses are usually used by small organizations (c) All the class A addresses have already been assigned (d) All the class C addresses have already been assigned (e) Class B addresses use 16 bits of host id field. 10- Which of the following is not a broadcast address? (a) IP address = 155.139.255.255, subnet mask = 255.255.0.0 (b) IP address = 155.139.251.255, subnet mask = 255.255.255.0 (c) IP address = 155.139.191.255, subnet mask = 255.255.224.0 (d) IP address = 155.139.252.255, subnet mask = 255.255.240.0 (e) IP address = 155.139.207.255, subnet mask = 255.255.240.0 11- Which of the following statement is wrong (a) CRC field in Ethernet Frame is used against errors (b) Checksum field in Packet Header is used against errors (c) Checksum field in Segment Header is used against errors (d) Acknowledgement field in Segment Header is used against errors (e) Parity bit in Ethernet Header is used against errors 12- Which of the following case there is no subnetting? (f) IP address = 55.139.251.222, subnet mask = 255.255.0.0 (g) IP address = 155.139.251.222, subnet mask = 255.255.0.0 (h) IP address = 205.139.251.222, subnet mask = 255.255.255.248 (i) IP address = 172.139.251.222, subnet mask = 255.255.192.0 (j) IP address = 172.139.251.222, subnet mask = 255.255.255.128 13- Which of the following is wrong about IP headers (a) TTL field is The Total Length field and measures the length of the packet (b) Version number is about version of the protocol (c) Checksum field allows detection of bit errors (d) ULP field is the upper layer protocol field and indicateds the payload contents (e) Header Length field indicates the length of the IP packet 14- Which one of the following does not have the same meaning as “Ethernet Address”? (a) MAC address (b) NIC Address (c) Physical Address (d) Global Address (e) Hardware Address 15- There are two four bit messages, 1010 and 1110. The first one is appended with an odd parity bit, the second one with an even parity bit. What are the values of the parity bits for the first and second messages respectively: (a) First is “1” second is “0” (b) First is “0” second is “1” (c) First is “1” second is “1” (d) First is “0” second is “0”

3 16- Which of the following is wrong about TCP header fields: (a) F flag is used for terminating connections (b) Credit window field is used for flow control (c) Sequence number field is used for orderliness and error control (d) S flag is used for signalling an error condition (e) Acknowledgement number is used to indicate the next segment expected 17- Which one of the following statements is wrong about error control in general (a) FCS is another name used instead of CRC (b) CRCs are error detection mechansims used in Link layer (c) Checksums are error correction mechansims used by IP and TCP (d) IP checksums only cover IP header (e) UPD checksums cover the entire segment 18- Which one of the statements about ARP is wrong (a) ARP entries are kept in tables for a limited amount of time (b) ARP stands for address resolution protocol (c) ARP is a link layer protocol (d) ARP allows mapping IP addresses to NIC addresses (e) ARP works only within the same subnet 19- Which of the following statement is wrong about TCP and UDP (a) TCP is a full duplex protocol. (b) TCP is a connection oriented protocol (c) UDP is a reliable protocol due to checksum field (d) TCP is a flow controlled protocol (e) UDP and TCP both use source and destination port numbers 20- Given the IP address 192.168.5.0, design a subnet mask that would allow 16 subnets. 21- A computer with an IP address f 195.75.39.187 and a mask of 255.255.255.224 want to send a packet to another computer with the IP address 195.75.39.198. Should it send it direct or should it send it to the default gateway? 22- An organization has the IP address 207.78.129.___ . (a) If this organization uses no subnetting, how many computers (including the router) can be on the network. (b) If this organization uses 255.255.255.192 as the subnet, how many computers can be on the subnets (i.e. all usable addresses in all subnets). (c) How many IP addresses are wasted between case (a) and case (b) – i.e due to subnetting? 23- You are given the IP address 131.161.___.___. You have to connect 5 offices in Clear Lake, Alvin, Pasadena, La Porte and Texas City. Determine the subnet mask and complete the following table. City Subnet Number Address of the first computer in this subnet Address of the last computer in this subnet Network Address Broadcast Address

4 ANSWERS TO QUESTIONS 1 - 23 1d, 2c, 3b, 4a, 5e, 6c, 7b, 8c, 9d, 10d, 11e, 12g, 13a, 14d, 15c, 16d, 17c 18c, 19c, 20 To get at least 16 subnet on a C class, we need at least 5 bits assigned to the Subnet, the mask would be: 255.255.255.248 21 The computers should use default gateway to send a packet. 22 (a) with no subnetting, the organization should be able to allocate up to 254 computer. (b) Using a subnet mask (assuming all 0 and all 1 subnets are not allowed), the organization should be able to have up to 62 computer per subnet on total of two subnets. (c) Thus the company would waste a total of 254 – ( 2 x 62 ) = 130 IP address due to subnetting. 23 City Subnet Number Address of the first computer in this subnet Address of the last computer in this subnet Network Address Broadcast Address Clear Lake 32 131.161.32.1 131.161.63.254 131.161.32.0 131.161.63.255 Alvin 64 131.161.64.1 131.161.95.254 131.161.64.0 131.161.65.255 Pasadena 96 131.161.96.1 131.161.127.254 131.161.96.0 131.161.127.255 La porte 128 131.161.128.1 131.161.159.254 131.161.128.0 131.161.159.255 Texas City 160 131.161.160.1 131.161.191.254 131.161.160.0 131.161.191.255

1 EXERCISE SET II NOTE : Assume that all 0 and all 1 subnets are usable unless otherwise stated 1- In a Cisco router which of the following is true about IOS and configuration file storage during the boot time: (a) Boot file comes from NVRAM and configuration file comes from RAM (b) Boot file comes from Flash and configuration file comes from NVRAM (c) Boot file comes from RAM and configuration file comes from NVRAM (d) Boot file comes from RAM and configuration file comes from Flash (e) Boot file comes from Flash and configuration file comes from RAM 2- In the following network, how many static routes will be needed for R2? (a) 1 (b) 2 (c) 3 (d) 4 (e) None of the above 3- Which of the following can NOT be used as a mask for a host IP address 192.193.194.80 (a) /25 (b) /26 (c) /27 (d) /28 (e) All of the above can be used as a mask for the given address 4- Two computers, PC1 and PC2 are on the same subnet of a small organization. PC1’s IP address is 200.200.200.169/27. Which of the following will be usable address for PC2? (a) 200.200.200.160 (b) 200.200.200.191 (c) 200.200.200.158 (d) 200.200.200.190 (e) 200.200.200.200 5- What is the maximum number of subnets that can be used in a class B network with a subnet mask 255.255.255.128? (a) 128 (b) 256 (c) 512 (d) 384 (e) None of the above 6- Which of the following is a not a field in IP header? (a) Type (b) Version (c) TTL (d) Checksum (e) TOS

2 7- In which of the following case there is NO subnetting ? (a) IP address = 126.126.126.126 subnet mask = 255.255.0.0 (b) IP address = 191.192.193.194 subnet mask = 255.255.255.0 (c) IP address = 192.193.194.195 subnet mask = 255.255.255.0 (d) IP address = 200.200.200.200, subnet mask = 255.255.255.128 8- Address Resolution Protocol is needed because: (a) IP address of a destination computer cannot be known in advance (b) MAC address of a destination computer cannot be known in advance (c) Subnet address of a destination computer cannot be known in advance (d) Network address of a destination computer cannot be known in advance (e) None of the above is the answer 9- Internet Control Message Protocol is used for the following reasons: (a) Router debugging and host management (b) Host management and router debugging (c) Debugging and error reporting (d) Router management and host debugging (e) None of the above 10- Which of the following is a broadcast address? (a) IP address = 190.191.253.255, subnet mask = 255.255.0.0 (b) IP address = 190.191.252.255, subnet mask = 255.255.255.128 (c) IP address = 190.191.192.255, subnet mask = 255.255.224.0 (d) IP address = 190.191.240.255, subnet mask = 255.255.240.0 (e) None of the above are broadcast addresses 11- In an IP packet, the header length and total length fields have the following binary values: 1100 and 00000001 00010100. Which of the following is true? (a) Header is 12 Bytes and Packet is 276 Bytes (b) Header is 36 Bytes and Packet is 120 Bytes (c) Header is 48 Bytes and Packet is 276 Bytes (d) Header is 36 Bytes and Packet is 276 Bytes (e) None of the above is true 12- Which one of the following statements about ARP is wrong (a) ARP replies are unicast to requester host (b) ARP requests are broadcast to all hosts (c) ARP allows mapping IP addresses to hardware addresses (d) ARP works within different subnets of the same Network ID (e) ARP entries are kept in arp tables for a limited amount of time 13- To which of the following address ranges, a computer with an IP address of 172.16.255.101/23 can send a packet directly (i.e. the destination is on the same subnet )? Select the largest applicable range: (a) 172.16.224.0 – 172.16.255.252 (b) 172.16.254.1 – 172.16.255.254 (c) 172.16.255.0 – 172.16.255.254 (d) 172.16.252.0 – 172.16.255.252 (e) None of the above address sets is in the direct range 14- An organization is assigned the Class C IP address 200.0.0.0 This organization has a headquarters location and 8 additional branch locations. Headquarters is assigned the first usable subnet ID. What is the subnet address of the fourth branch location? (a) 200.0.0.96 (b) 200.0.0.72 (c) 200.0.0.64 (d) 200.0.0.48 (e) None of the above

3 15- A computer, PC1, sends data to another computer, PC2, using parity method. Eight bits of data is appended with an odd parity bit to the left side of the data bits (i.e. parity bit becomes the leftmost bit). Assume that the data sequence is 11001001. Assume that the rightmost bit and the leftmost bits of the message (i.e. data and parity bit together) are “hit” by an electrical disturbance and they are inverted along the way. Which of the following statements will be true? (a) The received message by PC2 will be 111001001 and PC2 will be able to detect the errors (b) The received message by PC2 will be 011001000 and PC2 will be able to detect the errors (c) The received message by PC2 will be 111001000 and PC2 will not be able to detect the errors (d) The received message by PC2 will be 011001000 and PC2 will not be able to detect the errors (e) The received message by PC2 will be 010010001 and PC2 will not be able to detect the errors 16- Assume that a packet whose TTL field is set to 8 “dies” after 8 hops at a router. What kind of message will the router send to the source host? (a) ICMP “time exceeded” message (b) ICMP “low hop count setting” message (c) ARP response message (d) ARP request message (e) None of the above. 17- Traceroute program utilizes the following protocols and protocol features: (a) ICMP “destination unreachable”, ICMP “time exceeded” and IP “hop count” (b) ICMP “echo response” , ICMP “time exceeded” and IP “hop count” (c) ICMP “echo request”, ICMP “time exceeded” and IP “hop count” (d) ICMP “echo request” ICMP “destination unreachable”, and IP “TTL” (e) ICMP “time exceeded”, ICMP “echo request” and IP “TTL” 18- A company has two Ethernet networks connected with an internal router R2. The organization connects to the Internet via Houston node. On 192.168.1.0/27 network computer A has the MAC address aaaa.aaaa.aaaa, B has bbbb.bbbb.bbbb and so on. R1 has the MAC address 1111.1111.1111 and R2 has the MAC address 2222.2222.2222. R1 has the first IP address in the subnet, R2 has the next IP address in the subnet, A has the last IP address in the subnet, B has the IP address one less than A in the subnet and so on. Computer B needs to send a packet to an IP address 200.201.202.203. What would the source and destination IP and MAC addresses be? (a) Source: bbbb.bbbb.bbbb, 192.168.1.29, Destination: 2222.2222.2222, 192.168.1.2 (b) Source: bbbb.bbbb.bbbb, 192.168.1.30, Destination: 2222.2222.2222, 192.168.1.1 (c) Source: bbbb.bbbb.bbbb, 192.168.1.29, Destination: 1111.1111.1111, 200.201.202.203 (d) Source: bbbb.bbbb.bbbb, 192.168.1.30, Destination: 1111.1111.1111, 200.201.202.203 (e) none of the above 19- Refer the figure in previous question. If computer B needs to send a packet 192.168.1.69,, which IP address it will need to send an ARP to? (a) To 192.168.1.65 (b) To 192.168.1.2 (c) To 192.168.1.1 (d) To 192.168.1.28 (e) None of the above

4 20- Refer to the figure in Question 18. What would be the default gateway IP address for computer C? (a) 192.168.1.2 (b) 192.168.1.65 (c) 192.168.1.33 (d) 192.168.1.1 (e) None of the above 21- In Cisco routers two different prompts are used for different user privilege modes. Those prompts are: (a) “ : “ and “ # “ (b) “ > “ and “ # “ (c) “ : “ and “ > “ (d) “ > “ and “ : “ (e) None of the above 22- Given the IP address 96.216.215.214 and subnet mask of /17, which of the following is true about subnet ID and actual host ID? (a) SID=216.1.0 AHID=0.214.214 (b) SID=216.128.0 AHID=0.87.214 (c) SID=216.160.0 AHID=0.55.214 (d) SID=216.96.0 AHID=0.119.214 (e) None of the above 23- An organization uses a class A address with a mask 255.255.192.0. How many usable address are available in each subnet? (a) 2 10 – 2 (b) 2 11 – 2 (c) 2 12 – 2 (d) 2 13 – 2 (e) None of the above 24- Assume that you are told that the IP addresss 172.16.136.231 has the AHID value 8.231. Which of the following is the correct subnet mask for this IP? (a) /20 (b) /19 (c) /18 (d) /17 (e) None of the above 25- Which one of the following can not be assigned to a host as an IP address? (a) 200.200.200.79/29 (b) 200.200.200.96/26 (c) 200.200.200.80/27 (d) 200.200.200.32/26 (e) All of the above are assignable host addresses 26- A computer with IP address 10.248.224.225/16 wants to send a packet to another computer with IP address 10.249.224.225/16. What should it do? (a) the destination computer is on the same subnet and it should send it directly (b) the destination computer is on a different subnet and it should sendit via the default gateway (c) the destination computer address is not a legitimate address because it is a subnet address (d) the destination computer address is not a legitimate address because it is a broadcast address 27- The purpose of the checksum field in the IP header is: (a) To correct errors in IP header (b) To correct errors in IP payload (c) To correct errors in IP packet (d) To detect errors in IP header (e) None of the above

5 28- You need to subnet a network segment. How many subnetworks and hosts are available per subnet if you appy a /18 mask to the 120.0.0.0 network? (a) 8192 subnets and 8190 hosts (b) 1024 subnets and 16382 hosts (c) 16382 subnets and 4094 hosts (d) 4094 subnets and 8190 hosts 29- In order to configure a Cisco router for the first time, which of the following are required? (a) Console interface, PC Com Port, Hyperterminal Software (b) Console interface, Telnet, PC Com Port, Hyperterminal Software (c) Telnet, PC Com Port, Hyperterminal Software (d) Console interface, PC Com Port, Telnet --------------------------------------------------------------------------------------------------------------------------------- NARRATIVE QUESTIONS 30- A router receives a packet. It examines the packet header and finds the destination IP address in binary as follows: 01100111 10010001 11000010 01100100. The router uses /17 as subnet mask. What is the Network ID, Subnet ID and AHID values? Give the answers in decimal form. 31- A host computer “X” with IP address 200.180.150.119/26 can't communicate with another host “Y” with IP address 200.180.159.128/26. What is the problem? Explain.

6 32- You are given the IP address 180.181.0.0. You have to connect Clear Lake headquarters to 30 branch offices starting with: Alvin, Dickinson, Santa Fe and League City. There are more offices whose names are not needed here. Assign the first subnet to Headquarters and others to three cities listed above . You will assume that all 0 and all 1 subnets are NOT usable . Determine the subnet mask and fill out the first four rows of the following table: City Subnet Number Address of the first host in this subnet Address of the last host in this subnet Subnet Address Broadcast Address ANSWERS: 1b, 2b, 3d, 4d, 5c, 6a, 7c, 8b, 9c, 10b, 11c, 12d, 13b, 14c, 15d, 16a, 17e, 18c, 19b, 20d, 21b, 22b, 23e, 24d, 25a, 26b, 27d, 28b, 29a

7

1 1- What is the maximum number of hosts that can be used in a class B network with a subnet mask 255.255.252.0? (a) 510 (b) 511 (c) 1023 (d) 1022 (e) None of the above 2- What is the maximum number of subnets that can be used in a class C network with a subnet mask 255.255.255.224? (a) 14 (b) 16 (c) 30 (d) 6 (e) 32 3- Which of the following is a not in IP header? (a) TTL (b) TOS (c) Data Offset (d) ULP (e) Checksum 4- Which of the following statement about error detection is wrong? (a) CRC field in Ethernet Frame is used detect single bit errors (b) CRC field is a four byte field in the Ethernet Trailer (c) Checksum field in Packet Header is used detect errors in the header (d) Checksum field in the TCP header is used to detec errors in the segment (e) Another name for CRC is SFC 5- Which of the following case there is no subnetting? (a) IP address = 33.139.251.222, subnet mask = 255.255.0.0 (b) IP address = 133.139.251.222, subnet mask = 255.255.0.0 (c) IP address = 223.139.251.222, subnet mask = 255.255.255.248 (d) IP address = 133.139.251.222, subnet mask = 255.255.192.0 (e) IP address = 133.139.251.222, subnet mask = 255.255.255.128 6- Which of the following is wrong about the fields in IP header? (a) TTL field is hop count field and measures the hops packet makes (b) Version number is about version of the protocol (c) Checksum field allows detection of bit errors (d) Header Length field indicates how many bytes the packet header is. (e) ULP field is the upper layer protocol field and indicateds the payload contents 7- Which one of the following does not have the same meaning as “Ethernet Address”? (a) MAC address (b) NIC Address (c) Physical Address (d) Hardware Address (e) All of the above have the same meaning

2 8- There are three four bit messages, 1110 , 1100 and 0001. The first one is appended with an odd parity bit, the second and the third ones are appended with even parity bit. What are the values of the parity bits for the first, second and the third messages respectively: (a) First is “1” second is “0” third is “0” (b) First is “0” second is “1” third is “1” (c) First is “1” second is “1” third is “1” (d) First is “0” second is “0” “third is 0” (e) None of the above 9- Which of the following statements is wrong about Ethernet (a) Ethernet LANs use 6-byte source and destination addresses (b) Ethernet detects errors using CRC field (c) Ethernet uses a random access mechanism (d) Ethernet allows sharing of the communication medium (e) Ethernet access mechanism is called CDMA/CS 10- Which of the following is not a broadcast address? (a IP address = 129.7.255.255, subnet mask = 255.255.0.0 (b) IP address = 129.7.252.255, subnet mask = 255.255.255.0 (c) IP address = 129.7.191.255, subnet mask = 255.255.224.0 (d) IP address = 129.7.252.255, subnet mask = 255.255.240.0 (e) All of the above are broadcast addresses 11- Which of the following is wrong about Ethernet Addresses (a) Ethernet Addresses are 6 bytes long (b) Ethernet addresses are expressed in dotted decimal notation (c) Both source and destination Ethernet Addresses are carried in the Frame header (d) Manufacturer ID of the Ethernet card is expressed in the first three bytes of the Ethernet address (e) Ethernet Addresses are assigned to the cards at the factory 12- Which one of the statements about ARP is wrong (a) ARP replies are broadcast to all hosts (b) ARP requests are broadcast to all hosts (c) ARP allows mapping IP addresses to hardware addresses (d) ARP works only within the same subnet (e) ARP entries are kept in tables for a limited amount of time 13- A computer with an IP address f 208.75.39.173 and a mask of 255.255.255.224 can send a packet directly (i.e. the destination is on the same subnet ) to which of the following address ranges (pick the largest applicable range): (a) 208.75.39.161 - 195.75.39.190 (b) 208.75.39.161 – 195.75.39.179 (c) 208.75.39.161 – 195.75.39.192 (d) 208.75.39.161 - 195.75.39.200 (e) none of the above ranges is applicable 14- During the data exchange phase of a TCP connection, a computer “A” sends a segment with Credit Window = 8192 to a computer “B”. Assuming both networks use Ethernet as underlying link layer protocol (for MTU), how many full size segments can be sent from B to A without waiting for an acknowledgement? (a) 8 (b) 7 (c) 5 (d) 6 (e) none of the above

3 15- You are given the IP address 202.168.20.__ You have to connect 5 offices in Clear Lake, Alvin, Pasadena, La Porte and Texas City. You use 255.255.255.224 as your subnet mask. You assign the first available subnet ID to Clear Lake, second to Alvin, third to Pasadena etc. What is the broadcast address for the Pasadena (i.e. the third ) subnet? (a) 202.168.20.95 (b) 202.168.20.159 (c) 202.168.20.63 (d) 202.168.20.127 (e) none of the above 16- Which one of the following functions is not performed by TCP? (a) Error control (b) Sequencing (c) Acknowledgements (d) Flow Control (e) Time to Live 17- Which one of the following statements is wrong about TCP connections? (a) Starting handshake utilizes S, A and F flags. (b) No data can be exchanged prior to the starting handshake (c) Flow control utilizes Credit Window and ACK fields. (d) At the end of the data exchange, a 4-way handshake takes place. (e) “Pipe” metaphor is used to illustrate the orderly and error free data transfers associated with TCP connections. 18- Given the IP address 133.133.133.133 and subnet mask of 255.255.252.0, which of the following is true about subnet ID and actual host ID? (a) SID=128.0 AHID=5.133 (b) SID=132.0 AHID=1.133 (c) SID=130.0 AHID=3.133 (d) SID=133.0 AHID=0.133 (e) None of the above 19- Assume that you are told that the IP addresss 192.192.192.158 has the AHID value 14. Which is the correct subnet mask for this IP? (a) 255.255.255.192 (b) 255.255.255.224 (c) 255.255.255.240 (d) 255.255.255.248 (e) None of the above 20- Which one of the following is not a subnet address? (a) 208.216.164.96 with subnet mask 255.255.255.224 (b) 208.216.164.96 with subnet mask 255.255.255.192 (c) 208.216.164.64 with subnet mask 255.255.255.192 (d) 208.216.164.64 with subnet mask 255.255.255.224 (e) All of the above are legitimate subnet addresses 21- A computer with IP address 208.208.208.166 and a mask of 255.255.255.224 wants to send a packet to another computer with IP address 208.208.208.156. What should it do? (a) the destination computer is on the same subnet and it should send directly (b) the destination computer is on a different subnet and it should send via the default gateway (c) the destination computer address is not a legitimate address because it represents a subnet address (d) the destination computer address is not a legitimate address because it represents a broadcast address

4 22- Which of the following statements is wrong about TCP/UDP? (a) TCP is a full duplex protocol (b) UDP is a connection oriented protocol (c) UDP is a datagram protocol (d) TCP is a flow controlled protocol (e) TCP is a stream oriented protocol 23- Which of the following is wrong about TCP flags? (a) There are a total of 12 TCP flags of which S, F and A are the most important ones. (b) F flag is used during connection termination handshake (c) S flag is used during connection establishment phase (d) A flag is used to acknowledge receipt of segments (e) In the third handshake of connection establishment only A flag is set 24- An organization uses a class B address with a mask 255.255.224.0. How many usable address are available in each subnet? (a) 2 11 – 2 (b) 2 12 – 2 (c) 2 13 – 2 (d) 2 14 – 2 (e) 2 15 – 2 25- You need to subnet a Certkiller network segment. How many subnetworks and hosts are available per subnet if you appy a /28 mask to the 200.200.200.0 class C network? (a) 6 networks and 30 hosts (b) 30 networks and 6 hosts (c) 8 networks and 32 hosts (d) 32 networks and 8 hosts (e) None of the above 26- Your network uses the class B address 172.16.0.0. You need to support 459 hosts per subnet while accommodating the maximum number of subnets. Which mask would you use> (a) 255.255.0.0 (b) 255.255.128.0 (c) 255.255.224.0 (d) 255.255.254.0 (e) None of the above 27- Your ISP has assigned you the following IP address and subnet mask: 199.141.27.0, 255.255.255.240. Which of the following addresses can be allocated to hosts on the resulting subnet (select all that apply). (a) 199.141.27.2 (b) 199.141.27.175 (c) 199.141.27.13 (d) 199.141.27.11 (e) 199.141.27.208 (f) 199.141.27.112 28- Which of the following statements is wrong about DNS server/protocol? (a) Without a DNS server it is impossible to browse the Internet (b) DNS uses TCP as underlying transport protocol (c) Each PC must know the IP address of its DNS server in that organization (d) A DNS server is fully knowledgeable only about the organization it servers (e.g. xyz.com) (e) DNS servers of different organizations must interact with each other to resolve names.

5 29- A router R1 receives a packet and forwards it to the next router on the path (R2). When the packet leaves R2, TTL field of the packet contains the decimal number 11. Based on the data provide, which one of the following statements is wrong? (a) After R2, the packet can make 11 more hops. (b) When the packet left R1 the TTL field content was 12 (c) Each router increments the TTL field by 1. (d) All of the above statements are true. 30- Which one of the following Cisco command sequences is the correct one to configure telnet access to a Cisco Router. (a) Line vty 0, 4 login enable secret howdy (b) telnet line login enable password howdy (c) telnet login password howdy (d) line vty 0, 4 access password howdy (e) telnet login enable password howdy (f) line vty 0, 4 login password howdy 31- You issued the following commands in a Cisco Router in the sequence shown: enable, configure terminal, interface Ethernet 0. Which of the following prompt you will end up with? (a) Router# (b) Router(config)# (c) Router(config-if)> (d) Router(config-if)# (e) Router> 32- You are given the IP address 197.198.199.0. You have to connect the following offices: Clear Lake, Dickinson, Galveston and Pearland. Assume that all 0 and all 1 subnets are usable. Determine the subnet mask and fill out the first four rows of the following table: City Subnet Number Address of the first computer in this subnet Address of the last computer in this subnet Network Address Broadcast Address

1 EXERCISE SET 6 Assume that all 0 and all 1 subnets are usable unless otherwise stated 1- What is the maximum number of hosts that can be used in a class B network with a subnet mask 255.255.252.0? (a) 510 (b) 511 (c) 1023 (d) 1022 (e) None of the above 2- What is the maximum number of subnets that can be used in a class C network with a subnet mask 255.255.255.224? (a) 14 (b) 16 (c) 30 (d) 8 (e) 32 3- Which of the following is a not in IP header? (a) TTL (b) TOS (c) Type (d) ULP (e) Checksum 4- Which of the following statement about error detection is wrong? (a) CRC field in Ethernet Frame is used detect errors in the frame (b) CRC field is a four byte field in the Ethernet Trailer (c) Checksum field in Packet Header is used detect errors in the packet header (d) Parity bit is used to detect single bit errors (e) CRC and checksums are both used in software. 5- Which of the following case there is no subnetting (i.e. SID field is zero length)? (a) IP address = 33.139.251.222, subnet mask = 255.255.0.0 (b) IP address = 133.139.251.222, subnet mask = 255.255.0.0 (c) IP address = 223.139.251.222, subnet mask = 255.255.255.248 (d) IP address = 133.139.251.222, subnet mask = 255.255.192.0 (e) IP address = 133.139.251.222, subnet mask = 255.255.255.128 6- Which of the following is wrong about the fields in IP header? (a) TTL field is hop count field and measures the hops left for a packet to make (b) Version number is about version of the IP protocol (c) Checksum field allows detection of bit errors in the IP header (d) Header Length field indicates how many bytes the packet header is. (e) ULP field is the upper layer protocol field and indicateds the IP payload type 7- Which one of the following does not have the same meaning as “Ethernet Address”? (a) MAC address (b) NIC Address (c) Physical Address (d) Hardware Address (e) Global Address

2 8- There are three four bit messages, 1110 , 1100 and 0001. The first one is appended with an odd parity bit, the second and the third ones are appended with even parity bits. What are the values of the parity bits for the first, second and the third messages respectively: (a) First is “1” second is “0” third is “0” (b) First is “0” second is “1” third is “1” (c) First is “1” second is “1” third is “1” (d) First is “0” second is “0” “third is 0” (e) None of the above 9- Which of the following statements is wrong about Ethernet (a) Ethernet LANs use 6-byte source and destination addresses (b) Ethernet detects errors using CRC field (c) Ethernet is a type of LAN (d) Ethernet allows sharing of the communication medium (e) Ethernet networks always use coaxial cable 10- Which of the following is not a broadcast address? (a) IP address = 129.7.255.255, subnet mask = 255.255.0.0 (b) IP address = 129.7.252.255, subnet mask = 255.255.255.0 (c) IP address = 129.7.191.255, subnet mask = 255.255.224.0 (d) IP address = 129.7.252.255, subnet mask = 255.255.240.0 (e) All of the above are broadcast addresses 11- Which of the following is wrong about Ethernet Addresses (a) Ethernet Addresses are 6 bytes long (b) Ethernet addresses are expressed in dotted decimal notation (c) Both source and destination Ethernet Addresses are carried in the Frame header (d) Manufacturer ID of the Ethernet card is expressed in the first three bytes of the Ethernet address (e) Ethernet Addresses are assigned to the NIC cards at the factory 12- Which one of the statements about ARP is wrong (a) ARP replies are broadcast to all hosts (b) ARP requests are broadcast to all hosts (c) ARP allows mapping IP addresses to hardware addresses (d) ARP works only within the same subnet (e) ARP entries are kept in arp tables for a limited amount of time 13- To which of the following addresses, a computer with an IP address of 208.75.39.173 and a mask of 255.255.255.224 can send a packet directly (i.e. the destination is on the same subnet )? Select the largest applicable range: (a) 208.75.39.161 - 208.75.39.190 (b) 208.75.39.161 – 208.75.39.179 (c) 208.75.39.161 – 208.75.39.192 (d) 208.75.39.161 - 208.75.39.200 (e) none of the above ranges is applicable 14- An organization is assigned the IP address 172.16.0.0. This organization has a headquarters location and 14 branch locations. Headquarters is assigned the first usable subnet ID. What is the broadcast address of the second branch location? (a) 172.16.15.255 (b) 172.16.2.255 (c) 172.16.3.255 (d) 172.16.31.255 (e) None of the above

3 15- You are given the IP address 202.168.20.__ You have to connect 5 offices in Clear Lake, Alvin, Pasadena, La Porte and Texas City. You use 255.255.255.224 as your subnet mask. You assign the first available subnet ID to Clear Lake, second to Alvin, third to Pasadena etc. What is the broadcast address for the Pasadena (i.e. the third ) subnet? (a) 202.168.20.95 (b) 202.168.20.159 (c) 202.168.20.63 (d) 202.168.20.127 (e) none of the above 16- In IP packet header the “Total Length” field allows a maximum packet size of: (a) 20 Bytes (b) 60 Bytes (c) 65,535 Bytes (d) 1500 Bytes (e) None of the above 17- Which one of the following the acronyms is formally used to delineate Ethernet medium sharing mechanism? (a) LBT/LWT (b) LWT/LAT (c) CDMA/CS (d) CSMA/CD (e) None of the above 18- Given the IP address 133.133.133.133 and subnet mask of 255.255.252.0, which of the following is true about subnet ID and actual host ID? (a) SID=128.0 AHID=5.133 (b) SID=132.0 AHID=1.133 (c) SID=130.0 AHID=3.133 (d) SID=133.0 AHID=0.133 (e) None of the above 19- Assume that you are told that the IP addresss 192.192.192.158 has the AHID value 14. Which is the correct subnet mask for this IP? (a) 255.255.255.192 (b) 255.255.255.224 (c) 255.255.255.240 (d) 255.255.255.248 (e) None of the above 20- Which one of the following is not a subnet address? (a) 208.216.164.96 with subnet mask 255.255.255.224 (b) 208.216.164.96 with subnet mask 255.255.255.192 (c) 208.216.164.64 with subnet mask 255.255.255.192 (d) 208.216.164.64 with subnet mask 255.255.255.224 (e) All of the above are legitimate subnet addresses 21- A computer with IP address 208.208.208.166 and a mask of 255.255.255.224 wants to send a packet to another computer with IP address 208.208.208.156. What should it do? (a) the destination computer is on the same subnet and it should send directly (b) the destination computer is on a different subnet and it should send via the default gateway (c) the destination computer address is not a legitimate address because it represents a subnet address (d) the destination computer address is not a legitimate address because it represents a broadcast address

4 22- Which of the following is not an interface types for routers? (a) Ethernet is an interface type in a Router (b) Serial is an interface type in a router (c) Parallel is an interface type in a router (d) All of the above are router interface types 23- An organization uses a class B address with a mask 255.255.224.0. How many usable address are available in each subnet? (a) 2 11 – 2 (b) 2 12 – 2 (c) 2 13 – 2 (d) 2 14 – 2 (e) 2 15 – 2 24- You need to subnet a network segment. How many subnetworks and hosts are available per subnet if you appy a /28 mask to the 200.200.200.0 class C network? (a) 6 networks and 30 hosts (b) 30 networks and 6 hosts (c) 8 networks and 32 hosts (d) 32 networks and 8 hosts (e) None of the above 25- Your network uses the class B address 172.16.0.0. You need to support 459 hosts per subnet while accommodating the maximum number of subnets. Which mask would you use? (a) 255.255.0.0 (b) 255.255.128.0 (c) 255.255.224.0 (d) 255.255.254.0 (e) None of the above 26- A computer network is created with 5 routers and 6 Ethernet networks in a linear fashion. Each router is connected to neighbor routers using ethernet0 and ethernet1 interfaces. Other interfaces are not used. In this network how many static routes will be required at each router? (a) 4 (b) 3 (c) 6 (d) 5 (e) None of the above 27- A router R1 receives a packet and forwards it to the next router on the path (R2). When the packet leaves R2, TTL field of the packet contains the decimal number 11. Based on the data provide, which one of the following statements is wrong? (a) After R2, the packet can make 11 more hops. (b) When the packet left R1 the TTL field content was 12 (c) Each router increments the TTL field by 1. (d) TTL stands for Time to Live (e) Maximum possible TTL value is 255 28- In a Cisco router Flash memory is used to hold: (a) Configuration information (b) Operating System (IOS) (c) passwords (d) BIOS (e) None of the above

5 29- Which one of the following summarizes TCP functionality: (a) Addressing and routing (b) Local Transfers (c) Browsing (d) Medium sharing (e) End-to-end orderly and error free deliveries 30- We know that Class A addresses have 1-126, Class B addresses have 128-191 and Class C addresses have 192-223 in the first Byte of the address field. Assume that there were a Class “D” address. Also assume that Class D address is determined in the following way: The first three bits of the first byte of the address is always 1 and the fourth bit is always 0. According to this what would be the possible first Byte values for Class D addresses. Hint: You should compute this the same way we did in the classroom for the other addresses. (a) 192-240 (b) 200-240 (c) 224-240 (d) 224-239 (e) None of the above 31- Which of the following is not a legitimate IP address? (a) 192.168.0.1 (b) 1.255.255.254 (c) 191.191.191.191 (d) 223.256.255.254 (e) All of the above are legitimate IP addresses 32- You are given the IP address 196.196.196.0. You have to connect the following offices: Clear Lake, Dickinson, Galveston and Pearland. Assume that all 0 and all 1 subnets are usable. Determine the subnet mask and fill out the first four rows of the following table: City Subnet Number Address of the first computer in this subnet Address of the last computer in this subnet Subnetwork Address Broadcast Address

6 ANSWERS: 1 D, 2 D, 3 C, 4 E, 5 B, 6 D, 7 E, 8 E, 9 E, 10 D, 11 B, 12 A, 13 B, 14 E, 15 E, 16 C, 17 D, 18 B, 19 C, 20 A, 21 B, 22 C, 23 C, 24 E, 25 D, 26 A, 27 C, 28 B, 29 E, 30 D, 31 D 32: City Subnet Number Address of the first computer in this subnet Address of the last computer in this subnet Subnetwork Address Broadcast Address Clearlake 0 196.196.196.1 196.196.196.62 196.196.196.0 196.196.196.63 Dickinson 1 196.196.196.65 196.196.196.126 196.196.196.64 196.196.196.127 Galveston 2 196.196.196.129 196.196.196.190 196.196.196.128 196.196.196.191 Pearland 3 196.196.196.193 196.196.196.254 196.196.196.192 196.196.196.255

1 EXERCISE SET 7 1- Which of the following can NOT be used as a mask for a host IP address 200.200.200.47 (a) /28 (b) /27 (c) /26 (d) /25 (e) /24 2- Two computers, PC1 and PC2 are on two different subnets of a small organization. PC1’s IP address is 192.168.1.38/27. Which of the following will be usable address for PC2? (a) 192.168.1.32 (b) 192.168.1.55 (c) 192.168.1.64 (d) 192.168.1.93 (e) 192.168.1.31 3- What is the maximum number of subnets that can be used in a class B network with a subnet mask 255.255.254.0? (a) 64 (b) 62 (c) 128 (d) 254 (e) None of the above 4- Which of the following is a not a field in IP header? (a) TOS (b) Version (c) Hop Count (d) Checksum (e) Options 5- Which of the following case there is no subnetting ? (a) IP address = 126.127.128.129, subnet mask = 255.255.0.0 (b) IP address = 129.128.127.126, subnet mask = 255.255.0.0 (c) IP address = 191.192.193.194, subnet mask = 255.255.255.0 (d) IP address = 194.193.192.191, subnet mask = 255.255.255.128 (e) IP address = 192.192.193.194, subnet mask = 255.255.255.128 6- Which of the following field contents change as an IP packet travels across the Internet? (a) Version Field (b) Source IP field (c) Header Length Field (d) TTL Field (e) All of the above field values remain intact as the packet travels 7- Two computers, PC1 and PC2 have the following MAC addresses for the Ethernet cards in them: 054b.3c42.16fe and 054b.3c43.16fe. Which of the following statements is true ? (a) Two PCs have Ethernet cards by different manufacturers. (b) Two PCs have identical serial numbers (c) Two PCs have identical manufacturers (d) Those MAC addresses are not legitimate MAC addresses because they are too short. (e) None of the above

2 8- A computer, PC1, sends data to another computer, PC2, using parity method. Eight bits of data is appended with an even parity bit as the rightmost bit. Assume that the data sequence 10010011 is sent from PC1 to PC2. Assume that the very first bit (leftmost) and the parity bit are “hit” by an electrical disturbance and they are inverted along the way. Which of the following statements will be true? (a) The received message by PC2 will be 100100110 and PC2 will be able to detect the errors (b) The received message by PC2 will be 000100110 and PC2 will be able to detect the errors (c) The received message by PC2 will be 000100110 and PC2 will not be able to detect the errors (d) The received message by PC2 will be 000100111 and PC2 will be able to detect the errors (e) The received message by PC2 will be 000100111 and PC2 will not be able to detect the errors 9- Which of the following is true about ARP message encapsulation? (a) ARP messages are encapsulated into frames (b) ARP messages are encapsulated into packets which are in turn encapsulated into frames (c) ARP messages are encapsulated into segments which in turn are encapsulated into packets (d) Packets are encapsulated into ARP messages which in turn are encapsulated into frames (e) None of the above is true 10- Which of the following is a broadcast address? (a) IP address = 190.27.253.255, subnet mask = 255.255.0.0 (b) IP address = 190.27.252.255, subnet mask = 255.255.255.0 (c) IP address = 190.27.190.255, subnet mask = 255.255.224.0 (d) IP address = 190.27.248.255, subnet mask = 255.255.240.0 (e) None of the above are broadcast addresses 11- Which of the following is wrong about Ethernet frame format? (a) Ethernet headers are 18 Bytes long (b) Ethernet Type filed indicates what kind of payload is carried (c) CRC field is also known as FCS field (d) Ethernet Payload size can be at most 1500 Bytes (e) Ethernet Payload size must be at least 46 Bytes 12- Which one of the statements about ARP is wrong (a) ARP replies are broadcast to all hosts (b) ARP requests are broadcast to all hosts (c) ARP allows mapping IP addresses to hardware addresses (d) ARP works only within the same subnet (e) ARP entries are kept in arp tables for a limited amount of time 13- To which of the following address ranges, a computer with an IP address of 200.0.0.101/28 can send a packet directly (i.e. the destination is on the same subnet )? Select the largest applicable range: (a) 200.0.0.97 – 200.0.0.110 (b) 200.0.0.65 – 200.0.0.126 (c) 200.0.0.97 – 200.0.0.126 (d) 200.0.0.65 – 200.0.0.158 (e) None of the above address set is in the direct range 14- An organization is assigned the Class C IP address 192.168.5.0. This organization has a headquarters location and 8 branch locations. Headquarters is assigned the first usable subnet ID. What is the subnet address of the fourth branch location? (a) 192.168.5.48 (b) 192.168.5.96 (c) 192.168.5.64 (d) 192.168.5.72 (e) None of the above

3 15- An company has two Ethernet networks connected with an internal router R2. The organization connects to the Internet via Houston node. On 192.168.1.0/27 network computer A has the MAC address aaaa.aaaa.aaaa, B has bbbb.bbbb.bbbb and so on. R1 has the MAC address 1111.1111.1111 and R2 has the MAC address 2222.2222.2222. R1 has the first IP address in the subnet, R2 has the next IP address in the subnet, A has the next IP address in the subnet, B has the next IP address in the subnet and so on. Computer B needs to send a packet to an IP address 192.168.1.97. What would be the source and destination IP and MAC addresses be? (a) Source: bbbb.bbbb.bbbb, 192.168.1.2, Destination: 2222.2222.2222, 192.168.1.97 (b) Source: bbbb.bbbb.bbbb, 192.168.1.4, Destination: 2222.2222.2222, 192.168.1.97 (c) Source: bbbb.bbbb.bbbb, 192.168.1.4, Destination: 1111.1111.1111, 192.168.1.97 (d) Source: bbbb.bbbb.bbbb, 192.168.1.2, Destination: 1111.1111.1111, 192.168.1.97 (e) none of the above 16- Refer the figure in previous question. If computer B needs to send a packet 192.168.1.33,, which IP address it will need to send an ARP to? (a) To 192.168.1.33 (b) To 192.168.1.1 (c) To 192.168.1.2 (d) To 192.168.1.32 (e) None of the above 17- Refer to the figure in Question 15. What would be the default gateway IP address for computer X? (a) 192.168.1.2 (b) 192.168.1.1 (c) 192.168.1.33 (d) 192.168.1.65 (e) None of the above 18- In IP packet header the “Total Length” field has the value 1010. This means the IP header is: (a) 40 Bytes long (b) 20 Bytes long (c) 60 Bytes long (d) 10 Bytes long (e) None of the above 19- Which one of the following acronyms is formally used to delineate Ethernet medium sharing mechanism? (a) LBT/LWT (b) LWT/LAT (c) CDMA/CS (d) CSCD/MD (e) None of the above 20- Given the IP address 113.214.215.216 and subnet mask of /17, which of the following is true about subnet ID and actual host ID? (a) SID=214.1.0 AHID=0.214.216 (b) SID=214.128.0 AHID=0.87.216 (c) SID=214.160.0 AHID=0.55.216 (d) SID=214.96.0 AHID=0.119.216 (e) None of the above

4 21- Assume that you are told that the IP addresss 200.200.200.29 has the AHID value 5. Which of the following is the correct subnet mask for this IP? (a) /29 (b) /28 (c) /27 (d) /26 (e) None of the above 22- Which one of the following can not be assigned to a host as an IP address? (a) 200.200.200.79/29 (b) 200.200.200.96/26 (c) 200.200.200.80/27 (d) 200.200.200.32/26 (e) All of the above are assignable host addresses 23- A computer with IP address 172.16.211.129/25 wants to send a packet to another computer with IP address 172.16.211.127. What should it do? (a) the destination computer is on the same subnet and it should send directly (b) the destination computer is on a different subnet and it should send via the default gateway (c) the destination computer address is not a legitimate address because it represents a subnet address (d) the destination computer address is not a legitimate address because it represents a broadcast address 24- An organization uses a class A address with a mask 255.255.240.0. How many usable address are available in each subnet? (a) 2 11 – 2 (b) 2 12 – 2 (c) 2 13 – 2 (d) 2 14 – 2 (e) None of the above 25- You need to subnet a network segment. How many subnetworks and hosts are available per subnet if you appy a /23 mask to the 170.200.0.0 network? (a) 128 networks and 510 hosts (b) 256 networks and 254 hosts (c) 254 networks and 254 hosts (d) 64 networks and 1022 hosts (e) None of the above 26- Which one of the statements about CRCs and Checksums is correct? (a) CRCs are implemented in software (b) CRCs are implemented in hardware (c) Checksums are implemented hardware (d) They are both implemented in software (e) None of the above 27- Coaxial Ethernet cables are terminated with Terminators at two ends to: (a) To prevent connection of additional computers to the network (b) To prevent reflections (c) To prevent cable length to exceed maximum limit (d) To prevent collisions (e) None of the above is true

5 28- We know that Class A addresses have 1-126, Class B addresses have 128-191 and Class C addresses have 192-223 in the first Byte of the address field. Assume that there were a Class “D” address. Also assume that Class D address is determined in the following way: The first three bits of the first byte of the address is always 1 and the fourth bit is always 0. Assume also that there were a Class “E” address. Assume that class E addresses are determined in the following way: : The first four bits of the first byte of the address is always 1 and the fifth bit is always 0. What would be the range of values in the first Byte of class E addresses. (a) 252-255 (b) 224-254 (c) 224-240 (d) 239-255 (e) None of the above 29- The purpose of the TTL field in the IP header is: (a) To measure the Time To Live for IP packets in seconds (b) To limit the lifetime of a packet in seconds (c) To let the receiving host determine how many hops packet made (d) To prevent packets getting into endless routing loops (e) None of the above THE FOLLOWING QUESTIONS ARE NARRATIVE QUESTIONS. GIVE THE ANSWERS IN WRITTEN FORM 30- A router receives a packet. It examines the packet header and finds the destination IP address in binary as follows: 10100111 10010001 11000001 01100001. The router uses /25 as subnet mask. What is the Network ID, Subnet ID and AHID values? Give the answer in decimal form. 31- A host computer “X” with IP address 200.180.150.119/26 can't communicate with another host “Y” with IP address 200.180.150.128/26. What is the problem? Explain. 32- You are given the IP address 190.190.0.0. You have to connect Clear Lake headquarters to 16 branch offices starting with: Dickinson, Galveston and Alvin. There are more offices whose names are not needed here. Assign the first subnet to Headquarters and others to three cities listed above. Determine the subnet mask and fill out the first four rows of the following table: City Subnet Number Address of the first computer in this subnet Address of the last computer in this subnet Subnetwork Address Broadcast Address You can Use the back side of this page for your computations that you need to show

6 ANSWERS: 1 A, 2 D, 3 C, 4 C, 5 B, 6 D, 7 C, 8 E, 9 B, 10 B, 11 A, 12 A, 13 A, 14 C, 15 B, 16 E, 17 D, 18 D, 19 E, 20 B, 21 A, 22 A, 23 B, 24 B, 25 A, 26 B, 27 B, 28 E, 29 D 30 Network ID : 167.145 Subnet ID : 193.0 AHID : 0.97 31 Because both are in different subnets, they need router in between them to communicate. 32 City Subnet Number Address of the first computer in this subnet Address of the last computer in this subnet Subnetwork Address Broadcast Address Clear Lake 0 190.190.0.1 190.190.7.254 190.190.0.0 190.190.7.255 Dickinson 1 190.190.8.1 190.190.15.254 190.190.8.0 190.190.15.255 Galveston 2 190.190.16.1 190.190.23.254 190.190.16.0 190.190.23.255 Alvin 3 190.190.24.1 190.190.31.254 190.190.24.0 190.190.31.255

1 EXERCISE SET 8 1- Internet Control Message Protocol is used for the following reasons: (a) Router debugging and host management (b) Host management and router debugging (c) Debugging and error reporting (d) Router management and host debugging (e) None of the above 2- Which of the following is a broadcast address? (a) IP address = 169.254.253.255, subnet mask = 255.255.0.0 (b) IP address = 169.254.252.255, subnet mask = 255.255.255.128 (c) IP address = 169.254.192.255, subnet mask = 255.255.224.0 (d) IP address = 169.254.240.255, subnet mask = 255.255.240.0 (e) None of the above are broadcast addresses 3- In an IP packet, the destination IP address appears as 81 07 96 82 (in hexadecimal format). This IP address will have the following dotted decimal value: (a) 81.07.96.82 (b) 162.14.192.164 (c) 181.107.196.182 (d) 129.7.150.130 (e) None of the above is true 4- Which one of the following statements about ARP cache is wrong (a) Entries are purged after about 10 minutes of inactivity (b) A newly booted computer will have no entries in the cache (a blank cache) (c) Cache table has three columns: IP address, Source MAC address and Destination MAC address (d) The Windows computer command to look at cache table entries is “arp –a” (e) All of the above are true 5- To which of the following address ranges, a computer with an IP address of 192.168.100.101/28 can send a packet directly (i.e. the destination is on the same subnet )? Select the largest applicable range: (a) 192.168.100.97 – 192.168.100.110 (b) 192.168.100.102 – 192.168.100.102 (c) 192.168.100.97 – 192.168.100.116 (d) 192.168.100.97 – 192.168.100.126 (e) None of the above address sets is in the direct range 6- On serial router links, which one the following is the most economical subnet mask? (a) 255.255.255.0 (b) 255.255.255.252 (c) 255.255.255.224 (d) 255.255.255.255 (e) 255.255.255.240 7- A Router X sends a packet via a serial link to a neighboring router Y. The packet sent by X has the TTL value equal to 1. When packet arrives at Y, what will Y do? (a) Discards the packet and send and ICMP message to the source IP (b) Decrement the TTL value and forward the packet to the next router (c) Increment the TTL value and forward the packet to the next router (d) Send a “time exceeded” message to router X (e) None of the above is correct

2 8- In the following network, how many static routes will be needed for R2? (a) 4 (b) 5 (c) 2 (d) 3 (e) 6 9- Which of the following can NOT be used as a mask for a host IP address 169.254.203.255 (a) /18 (b) /19 (c) /20 (d) /21 (e) /22 10- Two computers, PC1 and PC2 are on the same subnet of a small organization. PC1’s IP address is 200.200.200.166/29. Which of the following will be a usable address for PC2? (a) 200.200.200.160 (b) 200.200.200.171 (c) 200.200.200.158 (d) 200.200.200.167 (e) None of the above 11- What is the maximum number of subnets that can be used in a class A network with a subnet mask 255.255.192.0? (a) 512 (b) 510 (c) 511 (d) 1024 (e) None of the above 12- The following sequence happens to be the first 26 Bytes that are contained at the beginning of an Ethernet frame (shown in Hexadecimal format). 4b 2c 33 05 12 fa 4b 2c 33 17 3d b7 08 00 45 00 00 c4 f2 3d 00 00 10 06 2c 39 …………. What is the source Ethernet address in this frame? (a) 3d b7 08 00 45 00 (b) 4b 2c 33 17 3d b7 (c) 17 3d b7 08 00 45 (d) 4b 2c 33 05 12 fa (e) None of the above

3 13- Consider the Bytes contained in the Ethernet frame provided in the previous question. What is the TTL value carried in the IP packet header in this frame? Use the IP Packet Header format given below to determine your answer. (a) 6 (b) 8 (c) 12 (d) 16 (e) None of the above 14- Refer to the following figure: Assume that PCA needs to send a packet to 192.168.3.10. What is the IP address whose MAC address inquires in its Address Resolution Protocol message? (a) 192.168.3.10 (b) 192.168.3.1 (c) 192.168.1.1 (d) 192.168.2.2 (e) 192.168.1.20 15- Which of the following is NOT and ICMP message type? (a) Echo Request (b) ARP (c) Time Exceeded (d) Destination Unreachable (e) All of the above are ICMP types 16- Two computers, A and B are connected to a subnet 192.168.1.0/27. Computer “A” has the IP address 192.168.1.11 and Computer “B” has the IP address 192.168.1.12. The administrator of computer “B” while entering subnet mask information types 255.255.255.240 (i.e. /28) by mistake. Both computers have the same default gateway assignment, 192.168.1.1. Keeping the subnet misconfiguration of computer “B” in mind, which of the following will be true? (a) Computer A will have the wrong broadcast address on the subnet (b) Computer B will have the wrong broadcast address on the subnet (c) Computer A will have the wrong subnet address (d) Computer B will have the wrong subnet address (e) Mistake will have no effect and everything will work fine.

4 17- Which one of the following is the last usable subnet if network mask 255.255.255.240 is used with 192.168.100.0? (a) 192.168.100.128 (b) 192.168.100.16 (c) 192.168.100.224 (d) 129.168.100.192 (e) None of the above 18- Subnetting wastes some address space. Waste is caused by subnet and broadcast addresses required for each subnet. Assume that you have 192.168.1.0 address space. If you use no subnetting, 192.168.1.0 and 192.168.1.255 are not usable addresses because these addresses designate the network and broadcast addresses. This means with NO subnetting wastes 2 addresses (i.e. cannot be used). Now assume that you use 192.1681.0/27. How many addresses will be wasted in this case? (a) 16 (b) 8 (c) 4 (d) 32 (e) None of the above 19- Refer to the figure below. What is the default gateway address for computers X and K? (a) 192.168.1.65 and 192.168.1.1 (b) 192.168.1.1 and 192.168.1.2 (c) 192.168.1.1 for both computers (d) 192.168.1.33 for both computers (e) None of the above 20- Refer the figure in previous question. The first computer “A” uses the first available IP addresses after R1 and R2 IP addresses on 192.168.1.0/27 subnet. Computer “K” uses the last usable IP address on this subnet. The IP addresses for A and K will be as follows: (a) 192.168.1.2 and 192.168.1.62 (b) 192.168.1.3 and 192.168.1.32 (c) 192.168.1.3 and 192.168.1.30 (d) 192.168.1.2 and 192.168.1.31 (e) None of the above 21- The first 16 Bytes contained in Ethernet frame are as follows (in hexadecimal format): 45 3c 12 69 eb 33 33 2d 30 1b 27 fb 08 00 49 00 ……… . The payload carried by this Ethernet frame is: (a) ARP Request (b) IP Packet (c) ICMP Message (d) UDP (e) None of the above 22- Given the IP Address in Binary: 10101001 00100111 10001001 00110010 , Mask:/29 . Which the following is true? (a) Net ID: 169.39 Subet ID: 137.32 AHID: 0.18 (b) Net ID: 169.39 Subet ID: 137.0 AHID: 0.50 (c) Net ID: 169.39 Subet ID: 137.16 AHID: 0.34 (d) Net ID: 169.39 Subet ID: 137.48 AHID: 0. 2

5 (e) None of the above 23- Given the IP address 100.101.204.112 and subnet mask of /17, which of the following is true about subnet ID and actual host ID? (a) SID=101.0.0 AHID=0.204.112 (b) SID=101.128.0 AHID=0.76.112 (c) SID=101.160.0 AHID=0.44.112 (d) SID=101.96.0 AHID=0.108.112 (e) None of the above 24- An organization uses a class A address with a mask 255.255.224.0. How many usable address are available in each subnet? (a) 2 10 – 2 (b) 2 11 – 2 (c) 2 12 – 2 (d) 2 13 – 2 (e) None of the above 25- Assume that you are told that the IP addresss 169.254.135.188 has the AHID value 7.188. Which of the following can be used as subnet mask for this IP address? (a) /20 (b) /19 (c) /18 (d) /17 (e) All of the above 26- Which one of the following can not be assigned to a host as an IP address? (a) 197.198.199.79/29 (b) 197.198.199.96/26 (c) 197.198.199.80/27 (d) 197.198.199.32/26 (e) All of the above are assignable host addresses 27- A computer with IP address 172.30.224.224/19 wants to send a packet to another computer with IP address 172.30.225.225. What should it do? (a) the destination computer is on the same subnet and it should send it directly (b) the destination computer is on a different subnet and it should sendit via the default gateway (c) the destination computer address is not a legitimate address because it is a subnet address (d) the destination computer address is not a legitimate address because it is a broadcast address 28- The purpose of the CRC field in the Ethernet header is: (a) To correct errors in Ethernet frame (b) To correct errors in Ethernet payload (c) To correct errors in IP packet (d) To detect errors in IP header (e) None of the above 29- You need to subnet a network segment. How many subnetworks and hosts are available per subnet if you appy a /18 mask to the 120.0.0.0 network? (a) 8192 subnets and 8190 hosts (b) 1024 subnets and 16382 hosts (c) 16382 subnets and 4094 hosts (d) 4094 subnets and 8190 hosts (e) None of the above 30- Which of TCP/IP Architecture layers are implemented in Hardware and which in software? (a) 1 HW, 2,3,4 SW (b) 1, 2 HW, 3,4 SW (c) All SW

6 (d) None of the above is true THE FOLLOWING QUESTIONS ARE NARRATIVE QUESTIONS. GIVE YOUR ANSWERS IN WRITTEN FORM IN THE SPACE PROVIDED UNDER THE QUESTIONS 31- In the following network, PCA sends an IP packet to PCB . TTL value at PCA is set to 8 . MAC addresses are as follows(in hexadecimal format): PCA: aaaa.aaaa.aaaa, R1-E0: 1010.1010.1010, R1-E1: 1111.1111.1111, R2:E0: 2020.2020.2020, R2-E1: 2121.2121.2121, PCB: bbbb.bbbb.bbbb. Determine the number of hops this packet makes. Then fill out the forms provided under the figure for every hop the packet makes. You may not need all the forms shown below.

7 32- You are given the IP address 197.198.199.0. You have to connect Clear Lake headquarters to branch offices shown in the network diagram below. You will assume that all 0 and all 1 subnets are NOT usable . Also assume that you have 192.168.1.0 address available to be used for serial links in the most economical way. The subnet mask you need to use for each City subnet is: ________________________ The subnet mask you need to use for T1 (serial) links is: ________________________ FILL OUT THE FOLLOWING TABLE: CITY Address of 1st host Address of last host Default Gateway Subnet Address Broadcast Address C. Lake L. City Alvin F. Wood Pasadena Assign IP addresses to serial links (T1 Lines) in the topology above and fill out the table below. Show the subnet masks in “/” notation along with IP addresses. R ‐ CL to R ‐ LC T1 Link => R ‐ CL S1 IP Address: R ‐ LC S0 IP Address: R ‐ LC to R ‐ AL T1 Link => R ‐ LC S1 IP Address: R ‐ AL S0 IP Address: R ‐ AL to R ‐ FW T1 Link => R ‐ AL S1 IP Address: R ‐ FW S0 IP Address: R ‐ FW to R ‐ PA T1 Link => R ‐ FW S1 IP Address: R ‐ PA S0 IP Address: R ‐ PA to R ‐ CL T1 Link => R ‐ PA S1 IP Address: R ‐ CL S0 IP Address:

8 ANSWERS 1c, 2b, 3d, 4c, 5a, 6b, 7a, 8a, 9e, 10e, 11d, 12b, 13d, 14c, 15b, 16b, 17e, 18a, 19a, 20c, 21b, 22a, 23b, 24d, 25e, 26a, 27a, 28e, 29c, 30a Question 31: HOP NUMBER 1 HOP NUMBER 2 Source IP Address 192.168.1.10 Source IP Address 192.168.1.10 Destination IP Address 192.168.3.10 Destination IP Address 192.168.3.10 Souce MAC Address aaaa.aaaa.aaaa Souce MAC Address 1111.1111.1111 Destination MAC Address 1010.1010.1010 Destination MAC Address 2020.2020.2020 TTL Value 8 TTL Value 7 HOP NUMBER 3 Source IP Address 192.168.1.10 Destination IP Address 192.168.3.10 Souce MAC Address 2121.2121.2121 Destination MAC Address bbbb.bbbb.bbbb TTL Value 6 Question 32: City Mask: 255.255.255.224 Serial Link Mask: 255.255.255.252 CITY Addr. Of 1st Host Addr. of last host Default Gateway Subnet Addr. B'Cast Addr. C. Lake 197.198.199.33 197.198.199.62 197.198.199.33 197.198.199.32 197.198.199.63 L. City 197.198.199.65 197.198.199.94 197.198.199.65 197.198.199.64 197.198.199.95 Alvin 197.198.199.97 197.198.199.126 197.198.199.97 197.198.199.96 197.198.199.127 F. Wood 197.198.199.129 197.198.199.158 197.198.199.129 197.198.199.128 197.198.199.159 Pasadena 197.198.199.161 197.198.199.190 197.198.199.161 197.198.199.160 197.198.199.191 R ‐ CL to R ‐ LC T1 Link => R ‐ CL S1 IP Address: 192.168.1.1/30 R ‐ LC S0 IP Address: 192.168.1.2/30 R ‐ LC to R ‐ AL T1 Link => R ‐ LC S1 IP Address: 192.168.1.5/30 R ‐ AL S0 IP Address: 192.168.1.6/30 R ‐ AL to R ‐ FW T1 Link => R ‐ AL S1 IP Address: 192.168.1.9/30 R ‐ FW S0 IP Address: 192.168.1.10/30 R ‐ FW to R ‐ PA T1 Link => R ‐ FW S1 IP Address: 192.168.1.13/30 R ‐ PA S0 IP Address: 192.168.1.14/30 R ‐ PA to R ‐ CL T1 Link => R ‐ PA S1 IP Address: 192.168.1.17/30 R ‐ CL S0 IP Address: 192.168.1.18/30

1 EXERCISE SET 9 1- Internet Control Message Protocol (ICMP) Type “Time Exceeded” reports the following problem: (a) Cache time in the arp table has exceeded and the entry will be deleted (b) Ping reply time has exceeded 1 seconds and the packet will be dropped (c) Time to live has reached to 0 (d) Destination computer’s expected response time of 5 seconds has exceeded (e) None of the above 2- Which of the following is NOT a broadcast address? (a) IP address = 169.254.175.255, subnet mask = 255.255.240.0 (b) IP address = 169.254.159.255, subnet mask = 255.255.224.0 (c) IP address = 169.254.182.255, subnet mask = 255.255.248.0 (d) IP address = 169.254.195.255, subnet mask = 255.255.252.0 (e) None of the above are broadcast addresses 3- In an IP packet, the destination IP address appears as ac 07 96 82 (in hexadecimal format). What class is this IP address? (a) Class A (b) Class B (c) Class C (d) This is not a legitimate IP address 4- Which one of the following is NOT a legimate IP address to assign to a host? (a) 192.168.255.254/27 (b) 172.16.0.255/23 (c) 169.254.256.221/24 (d) 10.11.12.13/16 (e) All of the above are legitimate IP addresses to assign to a host. 5- To which of the following address ranges, a computer with an IP address of 192.168.100.101/28 can send a unicast packet directly (i.e. the destination is on the same subnet )? Select the largest range applicable (a) 192.168.100.97 – 192.168.100.110 (b) 192.168.100.102 – 192.168.100.112 (c) 192.168.100.96 – 192.168.100.112 (d) 192.168.100.95 – 192.168.100.112 (e) None of the above address sets is in the direct range 6- On serial router links, which one the following is the most economical subnet mask (i.e. the one that wastes the least amount of address space)? (a) /31 (b) /30 (c) /29 (d) /25 (e) /24

2 7- In the following network, how many static routes will be needed for R6 ? Dashed lines are T1 links and solid lines are Ethernet networks. a) 3 b) 4 c) 5 d) 6 e) 7 8- Which of the following can NOT be used as a mask for a host IP address 222.133.134.135 (a) /26 (b) /27 (c) /28 (d) /29 (e) All of the above can be used as mask for the given address 9- Two computers, PC1 and PC2 are on the same subnet of an organization. PC1’s IP address is 172.16.238.254/21. Which of the following will be a usable address for PC2? (a) 172.16.239.255/21 (b) 172.16.224.254/21 (c) 172.16.240.255/21 (d) 172.16.233.254/21 (e) None of the above can be used as an address for PC2 10- What is the maximum number of subnets that can be used in a class A network with a subnet mask 255.255.224.0? (a) 2046 (b) 1022 (c) 510 (d) 1024 (e) None of the above 11- The following sequence happens to be the first 26 Bytes that are contained at the beginning of an Ethernet frame (shown in Hexadecimal format). What is the manufacturer ID for the destination Ethernet address in this frame? 4b 2c 33 05 12 fa 4b 2c 33 17 3d b7 08 00 48 00 00 c4 f2 3d 00 00 10 06 2c 39 …………. (a) 4b 2c 33 (b) 05 12 fa (c) 17 3d b7 (d) 08 00 45 (e) None of the above R1 e0 R2 s0 s1 e0 R3 e0 R4 s0 s1 e0 s0 s1 T1 T1 T1 R5 e0 R6 s0 s1 e0 T1

3 12- Consider the Bytes contained in the Ethernet frame provided in the previous question. What is the length of the IP header in this frame? Use the IP Packet Header format given below to determine your answer. “IHL” means IP Header Length. (a) 20 Bytes (b) 30 Bytes (c) 40 Bytes (d) 64 Bytes (e) None of the above 13- Refer to the following figure: Assume that PC with IP address 192.168.1.10 sends a packet to 192.168.3.10. What is the destination IP address in this packet and what is the destination MAC address of the frame that encapsulates this packet? (a) 192.168.3.10, ac.ab.aa.a9.a8.a7 (b) 192.168.3.1, ac.ab.aa.a9.a8.a7 (c) 192.168.1.1, a6.a5.a4.a3.a2.a1 (d) 192.168.3.10, a5.a6.a7.a8.a9.aa (e) None of the above 14- The purpose of the Ethernet “Type” field is similar to which of the IP header fields in function? (a) TTL (b) ULP (c) Version (d) Checksum (e) Header Length MAC Addresses: PCA: a1a2.a3.a4.a5.a6 PCB: a0.a2.a4.a6.a8.aa Houston E0: a6.a5.a4.a3.a2.a1 Dallas E0: a5.a6.a7.a8.a9.aa PCC: ac.ab.aa.a9.a8.a7

4 15- What is the subnet ID for the IP address 172.30.60.90/20? a) 48.90 b) 32.90 c) 16.90 d) 64.90 e) None of the above 16- What is the largest possible and usable host address ranges for the subnet 169.254.160.0/20? a) 4096 and 4094 b) 2 13 and 2 13 – 2 c) 2048 and 2046 d) 1024 and 1022 e) None of the above 17- Which one of the following is the last usable subnet if network mask /21 is used with 172.16.0.0? (a) 172.16.192.0 (b) 172.16.224.0 (c) 172.16.240.0 (d) 172.16.252.0 (e) None of the above 18- An Ethernet card receives a frame and computes the CRC and determines that the frame has an error. What does the card do? (a) Throws away the frame and does nothing else (b) Throws away the frame and sends an error message to sending computer (c) Reports to the network layer IP protocol about the error in the frame (d) Sends and ICMP error message to the source (e) None of the above 19- Refer to the figure below. Solid lines are Ethernet networks, dashed lines are T1 links. Assume that Routers R1, R2 and R4 have the first usable address assigned to E0 interfaces and R3 and R5 are assigned the second usable address to E0 interfaces. S0 interfaces are assigned the first usable and S1 interfaces are assigned the second usable addresses in the range. What is the default gateway address for computers PC2 and PC3? (a) 192.168.102.1 and 192.168.103.1 (b) 192.168.1.1 and 192.168.2.1 (c) 192.168.1.2 and 192.168.2.2 (d) 192.168.102.2 and 102.168.103.2 (e) None of the above

5 20- Refer the figure in previous question. Assume that PCs are assigned the first usable address in the range after the router interface addresses are assigned. What woud be the IP address for PC1 and PC2? (a) 192.168.101.2 and 192.168.102.2 (b) 192.168.101.3 and 192.168.102.3 (c) 192.168.101.2 and 192.168.102.3 (d) 192.168.101.3 and 192.168.102.2 (e) None of the above are usable addresses for PC1 and PC2 21- The first 16 Bytes contained in Ethernet frame and in its IP payload are as follows (in hexadecimal format): 45 3c 12 69 eb 33 33 2d 30 1b 27 fb 08 00 45 00 00 8a 3b 37 ……… What is the total length of this packet? (a) 138 Bytes (b) 8 Bytes (c) 20 Bytes (d) 256 Bytes (e) None of the above 22- Given the IP Address in Binary: 11001001 00100111 10001001 00110010 , and Subnet Mask:/28 , which of the following is true? (a) This is a Class C network with 4 bits in the subnet field (b) This is a Class B network with 12 bits in the subnet field (c) This is a Class C network with 5 bits in the subnet field (d) This is a class A network with 20 bits in the subnet field (e) None of the above 23- Given the IP address 112.113.114.115 and subnet mask of /12, which of the following is true about subnet ID and actual host ID? (a) SID=96.0.0 AHID= 17.114.115 (b) SID=112.0.0 AHID=1.114.115 (c) SID=80.0.0 AHID=33.114.115 (d) SID=64.0.0 AHID=49.114.115 (e) None of the above 24- An organization uses a class B address with a mask 255.255.255.192. How many usable address are available in each subnet? (a) 2 10 – 2 (b) 2 11 – 2 (c) 2 12 – 2 (d) 2 13 – 2 (e) None of the above 25- Assume that you are told that the IP addresss 169.254.143.144 has the AHID value 7.144. Which of the following can be used as subnet mask for this IP address? (a) /21 (b) /20 (c) /19 (d) /18 (e) None of the above 26- Which one of the following can be assigned to a host as an IP address? (a) 202.201.200.79/28 (b) 202.201.200.79/26 (c) 202.201.200.96/27 (d) 202.201.200.96/28 (e) All of the above are assignable host addresses

6 27- A computer with IP address 125.223.224.225/11 wants to send a packet to another computer with IP address 125.224.225.226/11. What should it do? (a) the destination computer is on the same subnet and it should send it directly (b) the destination computer is on a different subnet and it should sendit via the default gateway (c) the destination computer address is not a legitimate address because it is a subnet address (d) the destination computer address is not a legitimate address because it is a broadcast address 28- The difference between a “router” and a “node” is: (a) Routers route packet, nodes route segments (b) Routers route packets, nodes route frames (c) Routers operate on Network layer, Nodes operate at data link layer (d) There is no difference in function (e) None of the above are true 29- Which of the following acronyms officially designate the Ethernet medium sharing mechanism? a) LWT/LT b) CSMA/CD c) CDMA/CS d) LT/LBT e) None of the above 30- You are given the address 120.0.0.0/8. You have a large organization with offices in 285 cities. What subnet mask will you select? (a) /15 (b) /16 (c) /17 (d) /18 (e) None of the above 31- In the previous question, what would be the Subnet Address for the last city in your organization? Remember that all 0 and all 1 subnets are usable. (a) 120.142.0.0 (b) 120.143.0.0 (c) 120.255.30.0 (d) 120.255.29.0 (e) None of the above is true ANSWERS TO MULTIPLE CHOICE QUESTIONS 1c, 2c, 3b, 4c, 5a, 6b, 7d, 8d, 9d, 10e, 11a, 12e, 13e, 14b, 15e, 16a, 17e, 18a, 19a, 20c, 21a, 22a, 23b, 24e, 25a, 26b, 27b, 28d, 29b, 30c, 31e

7 THE FOLLOWING QUESTIONS ARE NARRATIVE QUESTIONS. GIVE YOUR ANSWERS IN WRITTEN FORM IN THE SPACE PROVIDED UNDER THE QUESTIONS 32- You are given the IP address 221.222.223.0/24. You have to connect Clear Lake headquarters to branch offices shown in the network diagram below. You will assume that all 0 and all 1 subnets are NOT usable . Your first task is to determine the subnet mask used for those cities to be used with the Ethernet networks. You need to perform computations and determine entries for the table given below The subnet mask you need to use for each City subnet is: ________________________ NOW FILL OUT THE FOLLOWING TABLE: CITY Address of 1st host Address of last host Default Gateway Subnet Address Broadcast Address C. Lake L. City Alvin F. Wood Pasadena

8 33- In Question 32, after using five subnets for the Ethernet networks for the given cities, you will end up with unused subnet(s). The last usable subnet space, you will divide into /30 subnets for your serial links. The unused subnet space should be able to accommodate all 5 serial links shown in the network diagram given in Question 32. After your computations, you need to fill out the entries for the table below Show the IP addresses assigned to T1 links in the table below R ‐ CL to R ‐ LC T1 Link => R ‐ CL S1 IP Address: R ‐ LC S0 IP Address: R ‐ LC to R ‐ AL T1 Link => R ‐ LC S1 IP Address: R ‐ AL S0 IP Address: R ‐ AL to R ‐ FW T1 Link => R ‐ AL S1 IP Address: R ‐ FW S0 IP Address: R ‐ FW to R ‐ PA T1 Link => R ‐ FW S1 IP Address: R ‐ PA S0 IP Address: R ‐ PA to R ‐ CL T1 Link => R ‐ PA S1 IP Address: R ‐ CL S0 IP Address:

Page 1 of 10 EXERCISE SET 10 Assume that all 0 and all 1 subnets are usuable unless stated otherwise 1- What does a computer do after it discovers a new MAC address with an ARP request-response process? (a) It uses it in the destination field of the frame to be sent and does nothing else (b) It places the information in the ARP cache and does nothing else (c) It gives the information acquired via ARP to IP protocol and does nothing else (d) It does “a” and “b” above (e) It does “b” and “c” above 2- Which of the following is a broadcast address? (a) IP address = 192.168.192.135, subnet mask = 255.255.255.240 (b) IP address = 192.168.192.175, subnet mask = 255.255.255.224 (c) IP address = 192.168.192.143, subnet mask = 255.255.255.240 (d) IP address = 192.168.192.191, subnet mask = 255.255.255.128 (e) None of the above are broadcast addresses 3- In an IP packet, the destination IP address appears as e2 b7 9f 82 (in hexadecimal format). What class is this IP address? (a) Class A (b) Class B (c) Class C (d) None of the above 4- What is the broadcast address for the third subnet if 200.1.2.0 is subnetted using /28 subnet mask? a) 200.1.2.63 b) 200.1.2.47 c) 200.1.2.31 d) 200.1.2.79 e) None of the above 5- Which one of the following is a legitimate IP address to assign to a host? (a) 192.168.255.195/30 (b) 172.16.0.255/24 (c) 169.254.256.127/25 (d) 10.11.12.13/16 (e) None of the above is a legitimate IP addresses to assign to a host. 6- Which of the following is NOT a usable address? a) 192.168.1.111/28 b) 192.168.1.112/27 c) 192.168.1.191/25 d) 192.168.1.225/27 7- You are building a network for the following 7 cities: Clear Lake, Alvin, Pasadena, League City, Galveston, Dickinson and La Porte. You are given the class C address 210.210.210.0. You are going to use the unused subnet space for serial links. How many serial links can be accommodated by the unused subnet space in this design? .a) 16 b) 8 c) 12 d) 4 e) None of these 8- Consider the previous question and assume that there are 6 cities instead of 7. What would be the broadcast address for the first serial link subnet? Assume that you are using the lowest available subnet value in the unused space left over from 6 cities for the first serial link. (a) 210.210.210.255 (b) 210.210.210.195 (c) 210.210.210.163 (d) 210.210.210.223 (e) None of the above

Page 2 of 10 9- A class C address if not subnetted will allow 254 usable addresses. If it is subnetted with mask /28, how many total usable address will be available in all the subnets together? a) 240 b) 224 c) 192 d) 248 e) None of the above 10- In the network diagram shown below, assume that all R1 and R3 router interfaces have the first usable address and R2 router interfaces have the second usable address in each range. Assume that you are trying to place static routes into router R1. As you know from your experiments, Cisco command for static routes is: ip route <destination network/subnet address> <destination subnet mask> <next hop router address> Which of the commands given below will accomplish the required task? .a) Commands 3, 5 b) Commands 1, 7 c) Commands 4, 8 d) Commands 2, 7 11- Which of the following can be used as a mask for the host IP address 169.254.207.255 (a) /19 (b) /20 (c) /21 (d) /22 (e) /23 12- Two computers, PC1 and PC2 are on the same subnet of an organization. PC1’s IP address is 172.31.182.254/22. Which of the following will be a usable address for PC2? (a) 172.31.183.1/22 (b) 172.31.183.255/22 (c) 172.31.184.224/22 (d) 172.31.179.254/22 (e) None of the above can be used as an address for PC2 13- How many computers can be placed on subnet 172.16.248.0/22? Assume that there is only one router attached to this subnet and that is the default gateway. (a) 1021 (b) 1022 (c) 1024 (d) 2046 (e) 2048 14- The following sequence happens to be the first 26 Bytes that are contained at the beginning of an Ethernet frame (shown in Hexadecimal format). What can you tell about the payload of this frame? 4b 2c 33 05 12 fa 4b 2c 33 17 3d b7 09 01 48 00 00 c4 f2 3d 00 00 10 06 2c 39 ……… PC1 E0 R3 R2 R1 S0 S0 192.168.1.32/30 E0 E0 192.168.1.48/28 192.168.1.16/28 PC3 PC2 E1 192.168.1.0/28 Command 1: ip route 192.168.1.0 255.255.255.0 192.168.1.16 Command 2: ip route 192.168.1.32 255.255.255.252 192.168.1.17 Command 3: ip route 192.168.1.32 255.255.255.252 192.168.1.18 Command 4: ip route 192.168.1.48 255.255.255.224 192.168.1.17 Command 5: ip route 192.168.1.48 255.255.255.240 192.168.1.18 Command 6: ip route 192.168.1.32 255.255.255.240 192.168.1.34 Command 7: ip route 192.168.1.32 255.255.255.248 192.168.1.16 Command 8: ip route 192.168.1.48 255.255.255.224 192.168.1.16

Page 3 of 10 (a) The payload is IP packet (b) Payload is ICMP message (c) Payload is not IP packet (d) Payload is UDP (e) None of the above 15- Which one of the following Ethernet frames has an IP packet payload with TTL field set to 15 hops? Remember that in the IP header, the TTL field is the 9 th Byte from the beginning of the packet header. a) eb 3c 33 45 d2 f4 4c 27 d3 17 08 00 45 00 48 00 00 c4 f2 3c 0f 00 10 06 2c 36 d3 …… b) 2b 3c 43 45 13 f4 4c 27 d3 17 08 00 08 05 45 00 00 b7 f2 4e 0f 00 0f 06 2d 38 23 ……… c) 6d 6c 33 45 12 f4 4c 27 d3 17 08 00 45 00 47 00 00 24 f2 3d 0f 00 10 06 1c 24 3c ……… d) cb 3c 33 35 12 f4 4c 27 d3 00 08 00 48 00 45 00 00 c4 f2 3d 0f 00 0f 06 2c a9 b3 ……… e) None of the above 16- In the following network, PCB has just been powered up and it needs to send a packet to PCC. After sending this packet, what would the contents of PCB ARP cache be? (a) IP Address: 192.168.3.10 MAC Address: ac.ab.aa.a9.a8.a7 (b) IP Address: 192.168.1.1 MAC Address: ac.ab.aa.a9.a8.a7 (c) IP Address: 192.168.1.1 MAC Address: a6.a5.a4.a3.a2.a1 (d) IP Address: 192.168.3.10 MAC Address: a5.a6.a7.a8.a9.aa (e) None of the above 17- The checksum field of the IP protocol at a PC shows that there is an error. This would mean that the error is in: (a) In the packet header (b) In the packet payload (c) In the entire packet (d) In the entire packet except the checksum field (e) None of the above 18- What is the subnet ID for the IP address (in hex form) ac 1c 9a d7 with subnet mask 255.255.248.0? a) 152.0 b) 144.0 c) 154.0 d) 160.0 e) None of the above 19- Trace route (tracert in Windows) command uses which of the following protocol features types and combinations? (a) It uses IP TTL field and ICMP protocol Echo, Echo Request and Time Exceeded Types (b) It uses ICMP protocol Echo, Echo Request and Time Exceeded Types (c) It uses IP protocol ULP field and ICMP Echo and Echo Request Types (d) It uses ARP protocol, IP protocol TOS field and all ICMP types (e) None of the above MAC Addresses: PCA: a1a2.a3.a4.a5.a6 PCB: a0.a2.a4.a6.a8.aa Houston E0: a6.a5.a4.a3.a2.a1 Dallas E0: a5.a6.a7.a8.a9.aa PCC: ac.ab.aa.a9.a8.a7

Page 4 of 10 20- IP header length field in an IP packet is 4 bits long. This means that the largest possible IP header length is the following: a) 20 Bytes b) 30 Bytes c) 40 Bytes d) 60 Bytes e) None of the above 21- ICMP is one of the important payloads that can be carried by the IP protocol. When the payload of a packet is ICMP, the ULP (upper layer protocol) field of the packet header will have the following decimal value: a) 0800 b) 20 c) 1 d) 6 e) None of the above 22- You are designing a network to accommodate 38 cities. You are given 172.22.0.0/16 class B address. What would be the subnet address of the last city? Note that all 0 subnet is usable. a) 172.22.38.0 b) 172.22.37.0 c) 172.22.148.0 d) 172.22.252.0 e) None of the above 23- What is the approximate value of the number 2 37 ? a) 64 million b) 128 million c) 32 billion d) 256 million e) None of the above 24- Given the IP address 99.113.114.115 and subnet mask of /12, which of the following is true about subnet ID and actual host ID? (a) SID=96.0.0 AHID= 17.114.115 (b) SID=112.0.0 AHID=1.114.115 (c) SID=80.0.0 AHID=33.114.115 (d) SID=64.0.0 AHID=49.114.115 (e) None of the above 25- An organization uses a class B address with a mask 255.255.255.192. How many usable address are there in each subnet? (a) 2 10 – 2 (b) 2 11 – 2 (c) 2 12 – 2 (d) 2 13 – 2 (e) None of the above 26- Which of the following computers is NOT in the same subnet as 172.29.237.254/23? a) 172.29.237.1 b) 172.29.236.254 c) 172.29.236.1 d) 172.29.238.1 e) All of the above are in the same subnet with 172.29.237.254/23 27- What is the reason for using “terminator” taps on coaxial Ethernet networks? a) To increase the speed of Ethernet b) To increase the length of coverage of Ethernet c) To eliminate reflections also known as electrical echo d) To reinforce reflections e) None of the above

Page 5 of 10 28- Which one of the following is NOT a subnet address? a) 172.25.248.0/23 b) 172.25.248.0/22 c) 172.25.248.0/21 d) 172.25.248.0/20 e) All of the above are subnet addresses 29- Which of the following is NOT a transport layer protocol in TCP/IP model? a) TCP b) UDP c) ARP d) All of the above are transport layer protocols 30- Assume that the Hyperterminal software in a PC communicates with a Cisco router using the console port and also using odd parity bit method. Assume that PC needs to send the two Bytes of data; 10011110 and 11101100. Assume that the rightmost bits are sent first and the parity bit is appended after the leftmost bit in the binary bit sequences given. Which one of the following would be the sent messages (i.e. parity bit and data combinations)? a) 010011110 and 011101100 b) 110011110 and 111101100 c) 100111100 and 111011000 d) 100111101 and 111011001 e) None of the above 31- The following binary number is the MAC address of an Ethernet network interface car (NIC): 10011100 01001100 10100001 10000001 11001101 10111100 What is the manufacturer ID of this card in hexadecimal? a) 9c 4c a1 b) 81 cd bc c) 9c 4c a1 81 d) 81 cd e) None of the above 32- You are given the address 100.0.0.0/8. You have a very large organization with offices in 893 cities. What subnet mask will you select? (a) /16 (b) /17 (c) /18 (d) /19 (e) None of the above

Page 6 of 10 33- You are given the IP address 200.1.2.0/24. You will build the network shown in the figure below. You are also told that all 0 and all 1 subnets are NOT usable. Your first task is to determine the subnet mask to be used in your design. Subsequently, you are required to fill the entries in the table given below for the first five cities in your design. ANSWER: We need a subnet mask of /28. It will result in the following entries: CITY Address of 1st host Address of last host Default Gateway Subnet Address Broadcast Address C. Lake 200.1.2.17 200.1.2.30 200.1.2.17 200.1.2.16 200.1.2.31 L. City 200.1.2. 33 200.1.2. 46 200.1.2. 33 200.1.2. 32 200.1.2. 47 Alvin 200.1.2. 49 200.1.2. 62 200.1.2. 49 200.1.2. 48 200.1.2. 63 La Porte 200.1.2. 65 200.1.2. 78 200.1.2. 65 200.1.2. 64 200.1.2. 79 Dickinson 200.1.2. 81 200.1.2. 94 200.1.2. 81 200.1.2. 80 200.1.2. 95 T1 Line PC-Last Clear Lake Subnet R-CL S1 E0 PC-First PC-Last League City Subnet R-LC S0 E0 PC-First PC-Last Alvin Subnet R-AL S0 E0 PC-First PC-Last Pasadena Subnet R-PA S0 E0 PC-First PC-Last Friendswood Subnet R-FW S0 E0 PC-First S0 S1 S1 S1 S1 T1 Line T1 Line T1 Line T1 Line PC-Last Santa Fe Subnet S0 E0 PC-First PC-Last Seabrook Subnet R-SB S0 E0 PC-First S1 S1 PC-Last La Porte Subnet R-LP S0 E0 PC-First PC-Last Dickinson Subnet R-DI S0 E0 PC-First S1 S1 T1 Line R-SF

Page 7 of 10 34- This question is a follow up to Question previous question. In this question you need to allocate addresses to the serial links for the network shown in previous question. For the serial links you are required to use the most economical mask. The unused subnets in previous question will be further subnetted to accommodate the serial links. You are asked to use the addresses closest to 200.1.2.255. That means you need to start assigning addresses from the higher end of your address space for the serial links. Your task is to show the serial link address to be used for the first five cities in the table given below. R-CL to R-LC T1 Link => R-CL S1 IP Address: 200.1.2.249/30 R-LC S0 IP Address:200.1.2.250/30 R-LC to R-AL T1 Link => R-LC S1 IP Address: 200.1.2.245/30 R-AL S0 IP Address: 200.1.2.246/30 R-AL to R-LP T1 Link => R-AL S1 IP Address: 200.1.2.241/30 R-LP S0 IP Address: 200.1.2.242/30 R-LP to R-DI T1 Link => R-LP S1 IP Address: 200.1.2.237/30 R-DI S0 IP Address: 200.1.2.238/30 R-DI to R-SB T1 Link => R-DI S1 IP Address: 200.1.2.233/30 R-SB S0 IP Address: 200.1.2.234/30 ANSWER: If we start to use the address space from the higher end and allocate /30 subnets, we will have the following (only the first 12 are shown) subnets: 200.1.2.252/30 200.1.2.248/30 200.1.2.244/30 200.1.2.240/30 200.1.2.236/30 200.1.2.232/30 200.1.2.228/30 200.1.2.224/30 200.1.2.220/30 200.1.2.216/30 200.1.2.212/30 200.1.2.208/30 . . . . . However, since all zero and all one subnets are not allowed, we cannot use 200.1.2.252/30 because for this subnet, the SID value will be all ones. Consequently, we need to start with 200.1.2.248/30 and go downwards assigning the addresses to serial links. For the serial link with the subnet address 200.1.2.248/30, the usable addresses will be 200.1.2.249 and 200.1.2.250. These are the addresses that will be assigned to the interfaces. Others are done in a similar way. The table above shows the answers for the asked serial links.

Page 8 of 10 ANSWERS ANSWER 1: After discovering the destination computer’s MAC address via ARP request-response process, the source computer uses it to send the packet that it couldn’t send earlier by encapsulating into a frame with the source and known destination MAC addresses. The computer also makes a record of the learned MAC address in the ARP Cache. Correct answer is “d”. ANSWER 2: For an address to be a broadcast address, all AHID bits must be set to “1” in binary. After testing each answer for this requirement using the giving mask and determining the AHID bits and if they are all set to 1, correct answer can be found as “c”. ANSWER 3: converting hexadecimal number “e2” to binary yields: 11100010. Since the leftmost three bits are 1 the answer will be none of the above because this address is neither Class A or Class B or Class C (as will be discussed in ISAM 5636, this is called a multicast address). ANSWER 4: The first three subnets for the given Class C address with the given subnet mask are the following: 200.1.2.0/28, 200.1.2.16/28, 200.1.2.32/28. The third subnet, 200.1.2.32/28, will have the broadcast address of 200.1.2.47. ANSWER 5: An address is a legitimate address to be assigned to a host if a) its Bytes have values between 0 and 255, b) it is not a broadcast address, c) it is not a subnet/network address. Based on those observations, “a” and “b” are broadcast addresses. “c” is not a legitimate address because it has value “256” in it. The correct answer is “d”. ANSWER 6: 192.168.1.111/28 is NOT a usable address because it is a broadcast address. ANSWER 7: For 7 cities, the required subnet mask is 255.255.255.224 (or /27). The subnet address 210.210.210.224/27 will be the only unused subnet. This means the address space 210.210.210.224 – 210.210.210.255 (total of 32 possible addresses) should be divided into smaller subnets (with mask /30) for serial links. The subnet mask /30 (or 255.255.255.252) allows 4 possible (and 2 usuable) addresses. This means it is possible to have 8 serial links in the unused subnet space. 8 serial links will take up 8x4=32 address space which is exactly the values from 210.210.210.224 through 210.210.210.255. ANSWER 8: If there are six cities, the 3-bit subnet field for those six cities will be: 000, 001, 010, 011, 100 and 101. This means the sixth city will have the subnet address of: 210.210.210.160/27. The remaining two subnets starting with addresses: 210.210.210.192 and 210.210.210.224 are available together for the serial links. The first serial link will have the subnet address: 210.210.210.192/30. This means the broadcast address for the serial link is 201.210.210.195. ANSWER 9: If a class C address is subnetted with mask /28, this will mean that there are 4 bits in the subnet field which will result in 16 subnets. AHID field also will have 4 bits allowing 14 usable (16 possible) addresses. Consequently, the total usable in all subnets together will be: 16 Subnets X 14 Usable address per subnet = 224. ANSWER 10: Router R1 needs two static routes for the networks that it is not directly attached to. Those two networks are: 192.168.1.32/30 and 192.168.1.48/28. For both networks, the next router address will be the E0 interface address of R2 (i.e. 192.168.1.18). The commands that will accomplish those two static routes are the following: ip route 192.168.1.32 255.255.255.252 192.168.1.18 ip route 192.168.1.48 255.255.255.240 192.168.1.18 ANSWER 11: If we convert the last two Bytes of 169.254.207.255 to binary, it will be as follows: 169.254.10001111.11111111. If subnet masks /20, /21, /22, /23 and /24 are used, this address will become broadcast address for all these subnets and hence it can NOT be used as a host address. The only mask that does not make this address a broadcast address is /19 and there for that is the only mask that can be used. ANSWER 12: First thing we need to do is to find out the subnet address for PC1. Converting the last two Bytes of 172.31.182.254 to binary will yield: 172.31.10110110.11111110. Applying /22 mask will result in the subnet address (last two Bytes binary) 172.31.10110100.00000000. For this subnet, the first usable address in the range will be: 172.31.10110100.00000001 and

Page 9 of 10 the last usable address in the range will be: 172.31.10110111.11111110. In dotted decimal, those numbers will be: 172.31.180.1 and 172.31.183.254 respectively. The only address that will fall into this range is 172.31.183.1/22. ANSWER 13: It should be noted that the word “computers” does not carry the same meaning as “hosts.” Host is any device that is attached to the network. Examples for host devices are computers, and routers . 172.16.248.0/22 subnet has 10 bits in its AHID field and consequently, it will allow for 1022 usable addresses. However, one of those addresses must be used for the router and as a result, the usable addresses for the computers after router address allocation is 1021. ANSWER 14: When the frame is parsed from left to right, the first six Bytes will be the destination MAC address (4b 2c 33 05 12 fa), the next six Bytes will be the source MAC address (4b 2c 33 17 3d b7) and the next two Bytes will be the Type field (09 01). Since the Type field content is NOT 0800 hexadecimal, we know that this frame is NOT carrying an IP packet. Since ICMP, UDP cannot be payloads for a frame (they are packet payloads), the answer should be “Payload is not an IP Packet” selection. ANSWER 15: To answer this question, we need to be familiar with the format of Ethernet frame and IP Packet. Ethernet frame header, which is 14 Bytes long, consists of 6 Bytes of Destination MAC address field, 6 Bytes of Source MAC address field and 2 Bytes of Type field. IP Packet Header format is shown in the figure below. Time to Live (TTL) field is the 9 th Byte from the beginning of the IP Packet or it is 9 + 14 = 23th Byte from the beginning of the Ethernet frame. Selection “d” above has the 23th Byte set to “0f” hexadecimal which would be 15 in decimal and hence the correct answer. ANSWER 16: It should be remembered that when the destination host is on the same network as the source host, ARP operation seeks to find out the MAC address of the destination host. However, if the destination host is on a different subnet or on a different network, then ARP operation will return the MAC address for the default gateway. In this example, source and destination computers are on different networks and hence, PCB will do an ARP operation to find out the MAC address of Houston Router which happens to be PCB’s default gateway. Consequently, after ARP operation is completed, in the ARP Cache, there will be an entry for the IP address and the MAC address of the Houston Router Ethernet interface, i.e. IP Address: 192.168.1.1, MAC Address: a6.a5.a4.a3.a2.a1 ANSWER 17: Checksum field in IP header is used to detect errors on IP header only. It will not detect errors in the payload field. ANSWER 18: First task is to convert this address into binary. This will yield: 10101100.00011100.10011010.11010111 (and in decimal 172.28.154.215). Applying the subnet mask 255.255.248.0 or /21 to the binary IP address will yield: 10101100.00011100.10011000.00000000 or in decimal: 172.28.152.0. This means the subnet ID for the given IP address is 152.0. ANSWER 19: Traceroute program sends ICMP Echo Request Messages to the destination computer in a packet whose TTL field is incremented by 1 in every new packet sent until the packet reaches the destination computer. Packets which cannot reach the destination computer because of insufficient TTL setting will be destroyed by intervening routers and those routers will send ICMP time exceeded messages to the source computer indicating insufficient TTL setting

Page 10 of 10 problem. Consequently, tracroute (tracert in Windows computers) uses IP TTL field, ICMP Echo Request and ICMP Echo Response messages for its implementation. ANSWER 20: The largest possible number in 4 bits is 1111 binary which is 15 decimal. Since IP header is measured in WORDS (1 WORD=4 Bytes), this would mean that the largest header length in IP packet can be 4 X 15 or 60 Bytes. ANSWER 21: The important ULP field values to remember are 1, 6 and 17 (Decimal values). ULP=1 means the IP Payload is ICMP, 6 means it is TCP and 17 means it is UDP. ANSWER 22: In order to accommodate 38 cities, we need 6 bits in the subnet field. 6 bits will have permutations varying from 000000 to 111111. The first city will have the value 000000, the second city will have the value 000001 and so on. The 38 th city will have the binary value 100101. The subnet address for this city will be 172.22.1001010 00.00000000 or in decimal it will be 172.22.148.0. ANSWER 23: 2 37 can be written as 2 10 2 10 2 10 2 7 which would yield an approximate value of 128 billion. Therefore the answer is None of the above. ANSWER 24: In determining the SID and AHID the first step is to convert the IP address into binary. In particular, HID (Host ID) part of the address need to be converted into binary because this is the part that is divided into SID and AHID components. Since this is a Class A address, we need to focus on the last three Bytes of the address and that needs to be converted to binary: 99.01110001.01110010.01110011. We can determine the subnet ID by performing an AND operation of IP address with the subnet mask. However, since we know that the subnet mask is /12 or it covers the first 12 bits, we can take the IP address in binary and make all the bits starting with bit 13 through bit 32 to 0. The result will be: 99.01110000.00000000.00000000. This would give us the subnet ID of 112.0.0 in decimal. We can determine AHID by subtracting 112.0.0 from 113.114.115 which would yield 1.114.115. ANSWER 25: The given mask, /25, leaves 7 bits for AHID field. Consequently, there will be 2 7 – 2 or 126 addresses in every subnet. Therefore the answer is “None of the above.” ANSWER 26: After converting 172.29.237.254 to binary (172.29.11101101.11111110) and performing a logical AND operation with the mask /23, it can be determined that the subnet address for the given IP address is: 172.29.1110110.00000000 or 172.29.236.0. The usable addresses in this subnet will be from 172.29.11100110.00000001 to 172.29.11100111.11111110 or from 172.29.236.1 to 172.29.237.254. The only given address choice that is NOT in this range is 172.29.238.1. ANSWER 27: Terminator taps are used to eliminate reflection that would otherwise occur at the end of the coaxial cable. ANSWER 28: Converting 172.25.248.0 to binary in the last two Bytes yields: 172.25.11111000.00000000. We know that a subnet address will have all AHID bit set to zero in binary. If we apply /20 mask to the address above, the AHID field will have the value 1000.00000000 which would make this address a non-subnet address. All the others will yield all zero AHID field values. ANSWER 29: ARP (Address Resolution Protocol) is a protocol that operates in Network Layer and hence it is NOT a transport layer protocol. ANSWER 30: Odd parity means a bit is appended at the end of the bit sequence in such a way that the total number of ones in the nine-bit sequence is an odd number. Therefore, the first bit sequence needs to be appended with a 0 and the second bit sequence is also need to be appended with a zero. The correct answer will be: 010011110 and 011101100 ANSWER 31: The manufacturer ID of an Ethernet card is the first three Bytes of the card’s Ethernet (MAC) address. After converting the given binary sequence to hexadecimal, the answer can be found as 9c 4c a1. ANSWER 32: To accommodate 893 cities, we need 10 bits which will give 1024 possible subnet ID choices (all zero and all 1 subnets are allowed). Consequently, this will make the subnet mask /18.

Page 1 of 9 EXERCISE SET 11 You need to assume that all 0 and all 1 subnets are USABLE unless otherwise stated 1- Which of the following is NOT a broadcast address? (a) IP address = 166.167.255.255, subnet mask = 255.255.0.0 (b) IP address = 166.167.251.255, subnet mask = 255.255.255.0 (c) IP address = 166.167.191.255, subnet mask = 255.255.224.0 (d) IP address = 166.167.252.255, subnet mask = 255.255.240.0 (e) IP address = 166.167.207.255, subnet mask = 255.255.240.0 2- A computer with an IP address 200.200.39.187 and a mask of 255.255.255.224 wants to send a packet to another computer with the IP address 200.200.39.194. Should it send it directly or should it send it to the default gateway? a) Send directly b) Send it to the default gateway c) Destination address is a broadcast address, can’t be sent d) Destination address is a subnet address, can’t be sent 3- Which of the following can NOT be used as a mask for a host IP address 200.200.200.80 (a) /25 (b) /26 (c) /27 (d) /28 (e) All of the above can be used as a mask for the given address 4- Two computers, PC1 and PC2 are on the same subnet of a small organization. PC1’s IP address is 193.194.200.164/28. Which of the following will be a usable address for PC2? (a) 193.194.200.160 (b) 193.194.200.191 (c) 193.194.200.158 (d) 193.194.200.190 (e) None of the above is a usable address for PC2 5- In which of the following case there is NO subnetting ? (a) IP address = 126.127.128.129 subnet mask = 255.255.0.0 (b) IP address = 191.190.189.188 subnet mask = 255.255.255.0 (c) IP address = 223.222.221.220 subnet mask = 255.255.255.0 (d) IP address = 20.200.200.200, subnet mask = 255.255.255.0 6- In an IP packet, the header length and total length fields have the following binary values respectively: 1001 and 00000001 10000100. Which of the following is true? (a) Header is 9 Bytes and Packet is 644 Bytes (b) Header is 20 Bytes and Packet is 388 Bytes (c) Header is 20 Bytes and Packet is 644 Bytes (d) Header is 36 Bytes and Packet is 644 Bytes (e) None of the above is true

Page 2 of 9 7- A company has two Ethernet networks connected with an internal router R2. The organization connects to the Internet via Houston node. On 192.168.1.0/27 network computer A has the MAC address aaaa.aaaa.aaaa, B has bbbb.bbbb.bbbb and so on. R1 has the MAC address 1111.1111.1111 and R2 has the MAC address 2222.2222.2222. R1 has the first IP address in the subnet, R2 has the next IP address in the subnet, A has the last IP address in the subnet, B has the IP address one less than A in the subnet and so on. Computer B needs to send a packet to an IP address 200.201.202.203. What would the source and destination IP and MAC addresses be? (a) Source: bbbb.bbbb.bbbb, 192.168.1.29, Destination: 2222.2222.2222, 192.168.1.2 (b) Source: bbbb.bbbb.bbbb, 192.168.1.30, Destination: 2222.2222.2222, 192.168.1.1 (c) Source: bbbb.bbbb.bbbb, 192.168.1.29, Destination: 1111.1111.1111, 200.201.202.203 (d) Source: bbbb.bbbb.bbbb, 192.168.1.30, Destination: 1111.1111.1111, 200.201.202.203 (e) none of the above 8- In the following network, how many static routes will be needed for R5 ? Dashed lines are T1 links and solid lines are Ethernet networks. a) 3 b) 4 c) 5 d) 6 e) 7 9- There is a computer with an IP address 200.201.202.173 and a mask of 255.255.255.224. To which of the following address ranges (pick the largest applicable range) can this computer send a packet directly (i.e. the destination is on the same subnet ): a) 200.201.202.164 - 200.201.202.190 b) 200.201.202.161 – 200.201.202.179 c) 200.201.202.162 – 200.201.202.192 d) 200.201.202.165 - 200.201.202.200 e) none of the above ranges is applicable R1 fa0/0 R2 s0 s1 fa0/0 R3 fa0/0 R4 s0 s1 fa0/0 s0 s1 T1   T1   T1   R5 fa0/0 s0

Page 3 of 9 10- Assume that you are told that the IP address 192.192.192.157 has the AHID value 13. Which of the following would be the correct subnet mask for this IP? (a) 255.255.255.192 (b) 255.255.255.224 (c) 255.255.255.240 (d) 255.255.255.248 (e) None of the above 11- Your network uses the class B address 169.138.0.0. You need to support 396 subnets while accommodating the maximum number of hosts. Which subnet mask would you use? a) 255.255.240.0 b) 255.255.248.0 c) 255.255.224.0 d) 255.255.255.0 e) None of the above 12- Which one of the following does NOT have the same meaning as “Ethernet Address”? a) MAC address b) NIC Address c) Physical Address d) Hardware Address e) Global Address 13- Which one of the following Cisco command sequences is the correct one to configure telnet access to a Cisco Router? a) Router(Config)#   line   vty   0,   4            Router(Config ‐ line)#   enable   secret   howdy               Router(Config ‐ line)#   login   b) Router(Config)#   telnet    line    4         Router(Config ‐ line)#   enable   password   howdy        Router(Config ‐ line)#   login   c) Router(Config)#   telnet     0     4           Router(Config ‐ line)#   password   howdy                     Router(Config ‐ line)#   login       d) Router(Config)#   line   vty   0,   4            Router(Config ‐ line)#   password   howdy                     Router(Config ‐ line)#   login       e) Router(Config)#   line   telnet    0,   4      Router(Config ‐ line)#   password   howdy                     Router(Config ‐ line)#   login       14- There are three four bit messages, 1011 , 0110 and 0110. The first one is appended with an odd parity bit, the second and the third ones are appended with even parity bits. What are the values of the parity bits for the first, second and the third messages respectively: (a) First is “1” second is “0” third is “0” (b) First is “0” second is “1” third is “1” (c) First is “1” second is “1” third is “1” (d) First is “0” second is “0” “third is 0” (e) None of the above is true 15- Which of the following statements is WRONG about Ethernet (a) Ethernet Frame has 6-byte source and 6-Byte destination addresses (b) Ethernet corrects errors using CRC field which is also called FCS field. (c) Ethernet is a type of LAN (d) Ethernet allows sharing of the communication medium (e) Ethernet is the first LAN invented 16- An organization is assigned the IP address 190.192.0.0. This organization has a headquarters location and 12 branch locations. Headquarters is assigned the first usable subnet ID. What is the broadcast address of the second branch location (Assuming the first subnet is assigned to the headquarters’)? (a) 190.192.47.255 (b) 190.192.31.255 (c) 190.192.2.255 (d) 190.192.3.255 (e) None of the above

Page 4 of 9 17- In an IP packet, the destination IP address appears as e2 b7 9f 82 (in hexadecimal format). What class is this IP address? (a) Class A (b) Class B (c) Class C (d) A subnetted address (e) None of the above 18- As you know, a class C address when not subnetted will allow 254 usable addresses. If a Class C address is subnetted with mask /28, how many total usable addresses will be available in all the subnets together? a) 240 b) 224 c) 192 d) 248 e) None of the above 19- Which one of the following is NOT a subnet address? (a) 200.201.202.96 with subnet mask 255.255.255.224 (b) 200.201.202.96 with subnet mask 255.255.255.192 (c) 200.201.202.64 with subnet mask 255.255.255.192 (d) 200.201.202.64 with subnet mask 255.255.255.224 (e) All of the above are legitimate subnet addresses 20- In a Cisco router Flash memory holds: (a) Configuration information (b) Operating System (IOS) (c) Enable and telnet passwords (d) BIOS (e) Packets 21- In the network diagram shown below, assume that all R1 and R3 router interfaces have the first usable address and R2 router interfaces have the second usable address. Assume that you are trying to place static routes into router R1. As you know from your class, Cisco command for static routes is: ip route <destination network/subnet address> <destination subnet mask> <next hop router address> Which of the commands given below will accomplish the required task? . a) Commands 1,7 b) Commands 3, 5 c) Commands 4, 8 d) Commands 2, 7 PC1 E0 R3 R2 R1 S0 S0 192.168.1.32/30 E0 E0 192.168.1.48/28 192.168.1.16/28 PC3 PC2 E1 192.168.1.0/28 Command 1: ip route 192.168.1.0 255.255.255.0 192.168.1.16 Command 2: ip route 192.168.1.32 255.255.255.252 192.168.1.17 Command 3: ip route 192.168.1.32 255.255.255.252 192.168.1.18 Command 4: ip route 192.168.1.48 255.255.255.224 192.168.1.17 Command 5: ip route 192.168.1.48 255.255.255.240 192.168.1.18 Command 6: ip route 192.168.1.32 255.255.255.240 192.168.1.34 Command 7: ip route 192.168.1.32 255.255.255.248 192.168.1.16 Command 8: ip route 192.168.1.48 255.255.255.224 192.168.1.16