An organisation has been granted a block of addresses with the mask /26. If the organisation creates 4 equal-sized subnets, how many addresses (including the special addresses) are available in each subnet? Show your calculations.
Give an example of a valid classful address that has the mask 255.0.0.0.
A subnetwork has the range of addresses: 22.214.171.124 to 126.96.36.199 inclusive. What is the direct broadcast address of this subnet?
What is the size of the IPv4 header with 9 bytes of options?
Explain why IPv6 datagrams do not incorporate a checksum
An address with port number was given as 188.8.131.52:63000
Is this a well-known port number or an ephemeral port number, give reasons for your answer.
In your own words, briefly explain the function of the garbage collection timer in RIP.
DNS name resolution is a process initiated by the browser for what purpose?
Identify the factual error in the following scenario:
“A datagram has been fragmented and must travel through several routers to reach the destination host. The last router in the journey re-assembles all the fragments and forwards the re-assembled packet onto the destination host.”
In the context of routing and forwarding, what does “direct delivery” mean? Explain in your own words.
When a router consults ARP during the forwarding process, what information is it looking for?
What is the purpose of the TTL field in the base header of an IPv4 datagram?
A classless address was given as “184.108.40.206/17” Explain why the prefix is critical to the function of the address.
In IPv6 does the size of the base header increase when options exist? Explain your answer.
Question 1 4 Marks
An organisation has been allocated the following block of classless addresses by its
Identify the address in this block that would be used as the network address, the range of addresses that can be used by network hosts, and the address that would be used as the direct broadcast address.
Question 2 4 Marks
A company has been granted a block of classless addresses which starts at
220.127.116.11/26. Create the following 4 subnets by calculating the subnet address for each subnet. Show your working.
(a) 1 subnet with 32 addresses
(b) 1 subnet with 16 addresses
(c) 2 subnets with 8 addresses each
Question 3 2 Marks
Consider this description: “A router uses various routing protocols to construct a logical routing table by entering networks it becomes aware of, it also enters into this table information about the next hop address and the interface leading to the next hop.” Is this a description of routing, or forwarding? Explain your answer.
Question 4 5 Marks
The diagram below shows the configuration of a hypothetical section of the Internet.
Construct the routing table of router R2 by copying and completing the following table in the Examination Answer Booklet. Put prefixes in CIDR format and in longest mask order.
Question 1 6 Marks
The IPv4 classful architecture has been wasteful and led to the rapid depletion of IPv4 addresses worldwide. Discuss why fixed-length classful addressing was a problem in terms of address allocation, and how subnetting and Classless Inter-Domain Routing (CIDR) helps to alleviate the problem.
Question 2 6 Marks
The period between the phasing out of IPv4 and the general adoption of IPv6 is referred to as the “transition period”. During this period, routers and hosts will need to support IPv4 and IPv6 at the same time. Discuss the main technical issues with having an Internet with mixed IPv4 and IPv6 routing, and the methods for overcoming those issues.
Question 3 6 Marks
The DNS is critical to the operation of the Internet. Discuss the DNS, being sure to cover what it is, what it does, and why it is critical to the operation of the Internet. Use your own words, do not copy or quote large passages from lecture notes or textbook etc.
Question 4 6 Marks
In ad hoc wireless networks, nodes (users) are grouped into areas called zones. Describe what makes up a ‘zone’, and briefly compare the protocols for routing within zones and between zones.