Question

What is the relationship between Iterative and Hierarchical/Recursive DNS lookups?

What are the three steps in a TCP session set-up?

Describe the relationship between IMAP and POP protocols.

Describe at least three improvements/changes made to the IPv6 header.

Which of the following OSI Layer 2 protocols does IPv6 Neighbor Discovery Protocol [NDP] completely replace?

1. Ethernet
2. ARP
3. ATM
4. Frame Relay

IPv6 was initially released in the 1990’s, but most Internet connected systems are still not currently using it. Provide at least two reasons or blockers that have slowed adoption.

Which 802.11 standard allows the most bandwidth? How much bandwidth does it support?

Which attack against 802.11 causes network nodes to disconnect using a spoofed frame? Why is this attack particularly dangerous

Bluetooth (802.15.1) has much more potential bandwidth than Zigbee (802.15.4). In what situations would Zigbee be a superior option to Bluetooth?

Answer 1

1.A DNS recursive query is between a DNS client(local computer) and ;its local DNS server. The local DNS server is responsible for answering the question that has come from its DNS clients. When this local DNS server could not resolve a name from its own database, then it will make an iterative query to other DNS server.

Example: Suppose local machine has a query like www.google.com and if the local DNS is a new machine and it has no record of the ip address of www.google.com. Then iterative query starts. In the iterative query other DNS can provide a referral if they do not know the requested IP address. Then the local server will go to the root domain name server and get back the ip address of .com server as referral. with this referral local DNS server will go to .com server and .com server gives back the IP address of Google DNS server. Then the local server get the IP address of www.google.com from Google DNS server.

POP3 : using POP3 mails only can be accessed from a single devices. After downloading the mail it will be deleted from the server.

IMAP: Mail can be accessed in multiple devices. This protocals helps to synchronize all devices with main server.

2) TCP stands for transmission control protocol. With the help of TCP data can be delivered successfully. TCP uses Three-Way-Handshake to establish a connection between client and server.

Example: Suppose a client has requested for a web page from a server. But before transmitting the web page TCP connection must be established using Three-Way-Handshake.

Step1: Client sends SYN segment to the server for synchronization

step2: Server replies with SYN-ACK. Here Server acknowledge the request coming from the client and ask client to open the connection.

step3: Client replies with ACK which stands for yes. Then the two way connection is established.

4) ARP does IPv6 Neighbor Discovery Protocol [NDP] completely replace.

5) i) implementation of IPv6 is costly.

ii) IPv4 address exhaustion was the major drive to implement IPv6. But NAT was already there in use. NAT can be implemented using low cost and also provide basic security.

802.11ac gives most bandwidth. Its approx 433 mbps.

6) 802.11 wireless lan networks are vulnarable to MAC address spoofing attack. The reason for this attack is management frames are sent as plain text and there is built-in encryption or authentication is present.

7) Zigbee can be used where application requires low data transfer rate and low power consumption. In case of traffic management system Zigbe can be used. Suppose to control traffic congestion city has installed numerous traffic sensors. connecting all these sensors using cable is cumbersome and expensive and also uses of wifi connection is expensive and Blutooth is also not be used as the distance between two sensors is long. In this case Zigbee canbe used.