Module 3.5- Network Models & Types

Question 1

OSI Model (Open Systems Interconnection)

Answer 1

• a seven-layer framework used to standardise the functions of a telecommunication or computing system
• each layer is responsible for a specific aspect of network communication
• the 7 OSl layers:
  1. Physical Layer
  2. Data Link Layer
  3. Network Layer
  4. Transport Layer
  5. Session Layer
  6. Presentation Layer
  7. Application Layer
• e.g. when you access a website, the data you send moves from Application Layer down to the Physical Layer before being sent across the network to the web server; on the receiving end, it moves back up the OSI layers

Question 2

Physical Layer (OSI Model)

Answer 2

• deals with the physical medium (cables and switches) and electrical signals that carry data

Question 3

Data Link Layer (OSI Model)

Answer 3

• responsible for node-to-node data transfer and error correction e.g. MAC addresses and Ethernet

Question 4

Network Layer (OSI Model)

Answer 4

• manages routing and forwarding of packets like IP addresses

Question 5

Transport Layer (OSI Model)

Answer 5

• provides reliable data transfer, error checking, and flow control for TCP and UDP

Question 6

Session Layer (OSI Model)

Answer 6

• manages sessions or connections between devices e.g. opening and closing connections

Question 7

Application Layer (OSI Model)

Answer 7

• closest to the end user, managing high-level services like file transfers, emails, and web browsing e.g. HTTP, FTP

Question 8

Presentation Layer (OSI Model)

Answer 8

• ensures that data is in a readable format for the application layer e.g. encryption, compression

Question 9

TCP/IP Model

Answer 9

• a more practical, four-layer framework used for modern internet communications
• maps to the OSl model but with fewer layers:
  1. Network Interface Layer
  2. Internet Layer
  3. Transport Layer
  4. Application Layer

e.g. when you stream a video, the Transport Layer (using TCP or UDP) ensures that data packets are delivered reliably, while the Internet Layer manages routing from your device to the streaming service

Question 10

Network Interface Layer (TCP/IP Model)

Answer 10

• combines the OSI Physical and Data Link layers, handling hardware and direct node communication

Question 11

Internet Layer (TCP/IP Model)

Answer 11

• corresponds to the OSI Network Layer, managing IP addresses and routing data

Question 12

Transport Layer (TCP/IP Model)

Answer 12

• similar to the OSI Transport Layer, handling data integrity and reliability (TCP, UDP)

Question 13

Application Layer (TCP/IP Model)

Answer 13

• combines the OSI Session, Presentation, and Application layers; manages protocols like HTTP, SMTP, and FTP