CS: How the Internet Works: Packets and Protocols Worksheet

Question 1

A student sends a photo to a friend over the internet. Explain why the photo is split into packets instead of being sent as one giant file.

Accepted Answer

The photo is split into packets so smaller pieces can travel across the network more easily. Packets can take different routes, and if one packet is lost, only that piece needs to be resent instead of the whole photo.

Question 2

Each packet usually has a header and data. Describe what the header does and what the data part contains.

Accepted Answer

The header contains information needed to deliver and reassemble the packet, such as source address, destination address, and packet order. The data part contains a piece of the actual message, file, image, or web page being sent.

Question 3

Put these steps in a reasonable order: A web page appears on your screen; DNS finds the IP address for the website name; your browser requests the web page; packets travel through routers; the server sends packets back.

Accepted Answer

A reasonable order is: DNS finds the IP address for the website name, your browser requests the web page, the server sends packets back, packets travel through routers, and the web page appears on your screen. Some packet travel happens during both the request and the response.

Question 4

What is an IP address, and why do devices on the internet need one?

Accepted Answer

An IP address is a numerical address used to identify a device or server on a network. Devices need IP addresses so packets know where to go and where to send replies.

Question 5

A packet is sent from Computer A to Server B. It passes through three routers. What is the job of each router?

Accepted Answer

Each router reads the packet's destination address and chooses the next best network path for the packet. Routers help move packets from one network to another until they reach the destination.

Question 6

Explain the difference between bandwidth and latency using an example.

Accepted Answer

Bandwidth is how much data can be sent in a certain amount of time, like the number of lanes on a highway. Latency is the delay before data starts arriving, like the time it takes a car to begin the trip and reach the destination.

Question 7

A video call freezes for a few seconds, then continues. Give two possible network reasons this might happen.

Accepted Answer

The video call might freeze because packets were delayed or lost, causing missing pieces of video or audio. It could also happen because the connection has low bandwidth or high latency, so the data cannot arrive smoothly.

Question 8

What is a protocol in computer networking? Give one example of an internet protocol.

Accepted Answer

A protocol is a set of rules that devices follow so they can communicate correctly. One example is HTTP, which is used for loading web pages, or TCP, which helps deliver packets reliably.

Question 9

TCP and UDP are two transport protocols. TCP checks that packets arrive and resends missing ones. UDP sends packets quickly but does not always check for every missing packet. Which protocol would be better for downloading a homework file, and why?

Accepted Answer

TCP would be better for downloading a homework file because the file must arrive completely and correctly. If packets are missing, TCP can request them again so the final file is not damaged.

Question 10

Which protocol would often be better for a live online game, TCP or UDP? Explain your choice.

Accepted Answer

UDP is often better for a live online game because speed is very important and a small amount of lost data may not matter. It is usually better for the game to keep moving than to pause while every lost packet is resent.

Question 11

A packet header says it is packet 4 of 10. Why is that number useful when the packets reach the destination?

Accepted Answer

The packet number helps the destination put all the packets back in the correct order. It also helps the destination notice if a packet is missing, such as packet 5 not arriving.

Question 12

DNS is sometimes described as the internet's phone book. Explain what DNS does.

Accepted Answer

DNS translates human-friendly domain names, such as example.com, into IP addresses that computers use to locate servers. This lets people use names instead of memorizing long numbers.

Question 13

A classmate says, "If a packet takes a different route from the other packets, the message will not work." Explain why this statement is not always correct.

Accepted Answer

The statement is not always correct because packets from the same message can travel by different routes and still be reassembled at the destination. As long as the needed packets arrive and can be put in order, the message can work.

Question 14

HTTPS is used by many websites. What does HTTPS add compared with regular HTTP, and why is it important?

Accepted Answer

HTTPS adds encryption and security checks to web communication. It is important because it helps protect private information, such as passwords or payment details, from being read or changed by others.

Question 15

A packet includes a simple error check value. The receiver calculates the value again and it does not match. What should the receiver do, and why?

Accepted Answer

The receiver should treat the packet as damaged and ask for it to be sent again if the protocol supports that. The mismatch suggests that some data changed during travel, so using the packet could create an incorrect message.

CS: How the Internet Works: Packets and Protocols

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