2022 internet service paper

Question 1

Explain the following terms in the context of networking and, in each case,
use an example to explain your answer:

Answer 1

“A protocol is a set of rules that define how devices communicate over a network. It ensures data is formatted, sent, and understood correctly between devices. For example, HTTP (Hypertext Transfer Protocol) is used when accessing websites. It allows a web browser to request content from a server and the server to send back the web page.”

Question 2

Explain the following terms in the context of networking and, in each case,
use an example to explain your answer:

Packet-switched Networks

Answer 2

Packet-switched networks split data into small packets, which may take different routes through the network to reach the destination. At the receiving end, the packets are reassembled into the original message. This method improves network efficiency and is more resilient to congestion or failure. A common example is using the TCP (Transmission Control Protocol) over the Internet, where data such as web pages or emails is sent in packets and reliably reconstructed.”

Question 3

A router has three interfaces. How many IP addresses does it have? Briefly
explain your answer. [5marks]

Answer 3

Each interface on a router needs its own unique IP address so it can communicate with a different network and transfer data correctly. Since this router has three interfaces, it would need three IP addresses in total.
For example, one interface might connect to a home network, another to a business network, and the third to the internet—each with its own IP address.

Question 4

What are the two resolution methods in DNS? Explain the procedure of
name resolution in each method, assuming that a user at Royal Holloway
(.rhul.ac.uk) wants to browse www.bbc.co.uk.

Answer 4

Recursive Resolution

Iterative Resolution

the recursive resolution
Example (user at Royal Holloway wants to visit www.bbc.co.uk):

The user’s computer asks the local DNS resolver: “What is the IP of www.bbc.co.uk?”

The resolver goes and asks the root server, which gives the address of the .uk server.

Then it asks the .uk server, which gives the .co.uk server.

Then it asks the .co.uk server, which gives the bbc.co.uk server.

Finally, it asks the bbc.co.uk DNS server, which gives the IP of www.bbc.co.uk.

The resolver sends the IP back to the user’s computer.

✅ The user only makes one request. The resolver handles the rest.

the Iterative Resolution
In this method, the resolver asks each server one by one, and each server replies with a hint for where to ask next.

Example:

The user’s resolver asks the root server, which says: “Ask the .uk server.”

Then it asks the .uk server, which says: “Ask the .co.uk server.”

Then it asks the .co.uk server, which says: “Ask bbc.co.uk.”

Finally, it asks bbc.co.uk’s server, which gives the IP of www.bbc.co.uk.

✅ The resolver follows the trail of answers until it gets the final IP.

Question 5

i. What is the User Datagram Protocol (UDP)?

Answer 5

UDP (User Datagram Protocol) is a simple and fast transport layer protocol used for sending data without setting up a connection. It is connectionless, meaning it does not guarantee delivery, order, or error checking.

UDP is useful for applications where speed is more important than reliability, such as online gaming, video streaming, or voice calls, where occasional data loss is acceptable.

Question 6

Why might an application developer choose to run an application over
UDP rather than TCP? Use an example to explain your answer.

Answer 6

“An application developer might use UDP when speed is more important than reliability, and some data loss is acceptable. UDP is faster because it is connectionless and does not perform error checking. A good example is video calls or online gaming, where error correction would cause unwanted delays.”