QUESTION 3 2.4-7 The local DNS server. Check all of the phrases below that state a true property of a local DNS server. The local DNS server record for a remote host sometimes different from that of the authoritative server for that host. The local DNS server holds hostname-to-IP translation records, but not other DNS records such as MX records. The local DNS server can decrease the name-to-IP-address resolution time experienced by a querying local host over the case when a DNS is resolved via querying into the DNS hierarchy. The local DNS server is only contacted by local host if that local host is unable to resolve a name via iterative or recursive queries into the DNS hierarchy.

QUESTION 3 2.4-7 The local DNS server. Check all of the phrases below that state a true property of a local DNS server. The local DNS server record for a remote host sometimes different from that of the authoritative server for that host. The local DNS server holds hostname-to-IP translation records, but not other DNS records such as MX records. The local DNS server can decrease the name-to-IP-address resolution time experienced by a querying local host over the case when a DNS is resolved via querying into the DNS hierarchy. The local DNS server is only contacted by local host if that local host is unable to resolve a name via iterative or recursive queries into the DNS hierarchy.

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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Check all of the phrases below that state a true property of a local DNS server. Group of answer choices A.The local DNS server can decrease the name-to-IP-address resolution time experienced by a querying local host over the case when a DNS is resolved via querying into the DNS hierarchy. B.The local DNS server holds hostname-to-IP translation records, but not other DNS records such as MX records. C.The local DNS server record for a remote host is sometimes different from that of the authoritative server for that host. D. The local DNS server is only contacted by a local host if that local host is unable to resolve a name via iterative or recursive queries into the DNS hierarchy.
Suppose within your web browser you click on a link to obtain a Web page. The IP address for the associated URL is not cached in your local host, so a DNS lookup is necessary to obtain the IP address. Suppose that three DNS servers are visited before your host receives the IP address from DNS. The first DNS server visited is the local DNS cache, with an RTT delay of RTT = 4 msecs. The second and third DNS servers contacted have RTTs of 45 and 24 msecs, respectively. Initially, let's suppose that the Web page associated with the link contains exactly one object, consisting of a small amount of HTML text. Suppose the RTT between the local host and the Web server containing the object is RTTHTTP = 9 msecs. Assuming zero transmission time for the HTML object, how much time elapses from when the client clicks on the link until the client receives the object? (Do not forget the TCP handshake(s).) 82 msecs O 91 msecs O 46 msecs O 67 msecs
1. A network has a DHCP server that manages a Class C network for IP addresses it gives out. Over the course of a week, 75- 80 people with devices come and go and their devices connect to the network each day. Often, by Wednesday or Thursday, people complain about not being able to connect to the network. Why can the lease life parameter be causing the problem?
Demonstrate how native authentication and authorization services are implemented step by step when a web client seeks access to protected resources on a web server. Which of the following two arguments in support of layered protocols is the most convincing? Provide examples to support your argument.
• IPV6 addresses use 128 bits to represent an address which includes bits to be used for subnetting. The second half of the address (least significant 64 bits) is always used for hosts only. Therefore, there is no compromise if we subnet the network. Use the Figure below to Create five subnets using route prefix 2001:db:acad::/48 (1 Marks) Routing Prefix Subnet ID Interface ID 48 Bits 16 Bits 64 Bits
True or false 6. Before sending a data packet into a packet-switching network, the source must determine all of the links that the packet will traverse between source and destination. 7. With non-persistent connections between a web browser and a web server, it is possible for a single TCP segment to carry two distinct HTTP request messages.
Show how to set up native authentication and authorization services for when a client connects to a web server and requests access to restricted resources. There are essentially two camps in favor of layering protocol: Prove your point by giving specific examples.
In the topology, Laptop 1 (Please assign an IP address from your design) sends a packet to Laptop 3 (Please assign an IP address from your design). Show the contents of the packets and frames at the network and data link layer respectively for each hop interface. You may assign any MAC address contains 12 Haxa Decimal Character at each hop interfaces between source and destination. A Sample MAC address is given in the topology.
Refer to the network figure above, showing two Ethernet Subnets connected through an IP Router, answer the following question 1-5. The devices in each subnet are connected locally to each other through layer two intermediate devices such as Ethernet switch and ethernet hub. For each device in the subnets, both its Internet Protocol (IP )address and its MAC address (also called the Physical address or the Ethernet address are shown. The subnet mask used by all devices is 255.255.255.240 (which is the same as the prefix length “/28”). 1. If Client #1 wants to send a broadcast packet to all the devices on the left subnet (containing client #1, client #2, client #3) what destination IP address should be used? (Mention in both binary and decimal format.) 2. What is the first and last assignable IP address for the left subnet above (containing client #1 and #3)? (Mention in both binary and decimal format.)
Tracing through Layers Given the following scenario, trace out the path the packets will follow in the diagram provided. An alternate method of specifying your answer is given that requires no drawing Scenario: Your laptop A opens a web page from the server F, and the web caching server keeps a copy of the page on its way back to you. A second user A' (who takes your place on the diagram) is on the same LAN as you, connected also to Router B, and opens the same web page. Draw the path the HTTP message requesting the page would take from its origin point at A' to its destination point where the packet would go no further. See diagram for more info
For DNS query, it is natural to expect that the local DNS server may not know how to resolve an address. In this case, further queries will be made by this local DNS server. If a hacker can find "a way" to make a certain DNS server report back the wrong IP address, then anyone trying to get to one Web address will be sent to a bogus one, without any obvious way for the user to detect that anything is wrong. Likewise, email could be delivered to the wrong destination. 1) Describe two possible attacks to make the resolver report the wrong IP address.
This comprehensive exposition of DNS operations includes sections on iterated and non-iterated requests, authoritative and root servers, and DNS records.