PART A 21 MARKS
How does the destination host know whether a datagram received is fragmented or not?
An organisation has been granted a block of class C addresses. If the block is divided into 8 equal-sized subnets, how many addresses (in total) are available in each subnet? Show your calculation.
Write out in abbreviated hex form the loopback address in IPv6.
What is the maximum size of the IPv4 header?
What is the purpose of an access point in a Wi-Fi network?
What is the size of the port address field in a UDP header?
Which field in the IPv6 header can point to the extension header?
What is the IEEE standard for wireless LANs?
What is the key difference between the topology of Extended Service SET (ESS) and mesh wireless networks?
Give an example of an address a router would use to send a packet to all other hosts on its subnet?
What are the purposes of ICMP messages?
What is the purpose of flow control in networking?
Which timer schedules the sending out of regular update messages in RIP?
What is the size of the base header in IPv6 expressed in bytes?
Question 1 4 Marks
An organisation has been allocated the following block of classless addresses by its ISP: 126.96.36.199/29
List all the addresses in this range and identify those that can be used by the hosts, the network address and the direct broadcast address. Show your working.
Question 2 4 Marks
A company has been granted a block of addresses which starts at 188.8.131.52/23.
They have decided to create 6 subnets for initial needs as follows:
2 subnets with 64 addresses each
2 subnets with 32 addresses each
2 subnets with 16 addresses each
Define the six subnets by calculating the prefix, first address and last address of each subnet. Show your working.
Question 3 2 Marks
The following IPv6 routing description contains a basic error. Identify the error and provide a brief explanation of your answer.
“A router in an IPv6 network receives a packet with an MTU of 1,518 bytes, and determines that the next hop, also an IPv6 network, has an MTU of 576 bytes. To ensure that the packet will be handled correctly at the next destination, the router fragments the packet into three fragments of 506 bytes each and forwards each fragment in its own packet.”
Question 4 5 Marks
The figure below shows the configuration of a hypothetical section of the Internet.
Construct the routing table of router R3 by copying and completing the following table into the Examination Answer Booklet.
Question 1 6 Marks
Compare and contrast connectionless packet switching and virtual circuit packet switching. Give an example protocol of each.
Question 2 6 Marks
Explain how Network Address Translation (NAT) helps to alleviate the IPv4 address shortage.
Question 3 6 Marks
a) In your own words, explain the difference between DHCP’s static and dynamic address allocation options.
b) Briefly discuss when it might be appropriate to use static and dynamic address allocation – give an example of each.
Question 4 6 Marks
Briefly describe the Destination-Sequenced Distance Vector (DSDV) routing protocol used for routing in wireless ad hoc networks.