14.1 Protocols

Question 1

Why is a protocol essential for

communication between computers?

Answer 1

• Protocol represents the agreed rules for communication between two systems.
• Includes mode of connection, packet size, compression mode, etc.
• Without these rules, it is not possible to ensure successful communication.

Question 2

State the four-layer structure for TCP/IP protocols.

Answer 2

Application
Transport
Internet/Network
Link layer

Question 3

Purpose and function of the Application layer.

Answer 3

Contains all the programs that exchange data, such as web browsers or server software and sends files to the transport layer.

This layer allows applications to access services in other layers and defines the protocols that any app uses for the exchange of data.

HTTP/SMTP/POP3/FTP/IMAP

Question 4

Purpose and function of the Transport layer.

Answer 4

Transport layer regulates the network connections, ensuring the packets arrive in sequence, without errors, by retransmitting packets if they become lost or corrupted.

eg TCP

Question 5

Purpose and function of the Internet layer.

Answer 5

Identifies the intended network and host. eg IP (internet protocols)

Question 6

Purpose and function of the link layer.

Answer 6

Identifies and moves traffic across local segments, encapsulates IP packets into frames for transmission, maps IP addresses to mac addresses, and ensures correct protocols are followed.

eg Ethernet, WiFi, Bluetooth

Question 7

State the steps which take place when the TCP/IP is used to send a message to a node on a different LAN.

Answer 7

• Message is split into packets.
• Each packet is given a header, including destination IP, file size
• Packets forwarded from one LAN to the other LAN
• Packets may take different routes, then reassembled at the destination.

Question 8

Function of the TCP protocol.

Answer 8

1) Allows applications to exchange data
2) Establishes and maintains connection until data exchange is completed.
3) Reassembles packages into the correct order.

Question 9

Function of the IP Protocol.

Answer 9

1) Routes the packets around the network

2) Adds the source/destination address to the header of each packet.

Question 10

Describe TCP/IP protocol suite.

Answer 10

• A layered stack with 4 layers.
• Uses a set of protocols for transmission of data.
• ATIL.

Question 11

Explain how Bittorrent works?

Answer 11

• BitTorrent client software made available.
• File is split into small pieces.
• A computer joins the swarm by downloading the torrent descriptor file.
• Once the computer has a piece of the file it can become a seed and upload that piece to other members of the swarm.
• A leech refers to a seed that does more downloading than uploading.

Question 12

What is a tracker?

Answer 12

Central server that has data on peers uploading/downloading files.

Question 13

What is a seed?

Answer 13

peer computer that is uploading downloaded content.

Question 14

What is a swarm?

Answer 14

All connected peer computers that have part of the file to be downloaded.