1.1 The OSI Model

Question 1

What is the OSI model?

Answer 1

The Open Systems Interconnection Reference Model; a guide for understanding how data moves across a network.

Question 2

Is the OSI model a protocol suite?

Answer 2

No, it is not a protocol suite; it’s a reference model with unique protocols at each layer.

Question 3

What phrase can help remember the OSI layers?

Answer 3

“All People Seem To Need Data Processing.”

Question 4

What does the Physical Layer (Layer 1) involve?

Answer 4

The physics of the network, including signaling, cabling, and connectors.

Question 5

What does the Physical Layer (Layer 1) focus on?

Answer 5

it focuses on physical aspects like cabling and connectors.

Question 6

What troubleshooting steps are associated with the Physical Layer? (Layer 1)

Answer 6

Fixing cabling issues, running loopback tests, testing/replacing cables, and swapping adapter cables.

Question 7

What is the primary function of the Data Link Layer? (Layer 2)

Answer 7

It acts as the basic network “language” and manages communication at the data link level.

Question 8

What are the protocols related to the Data Link Layer? (Layer 2)

Answer 8

Data Link Control (DLC) protocols and MAC (Media Access Control) addresses.

Question 9

What is the Data Link Layer (Layer 2) often called?

Answer 9

The “switching” layer.

Question 10

What does the Network Layer (Layer 3) handle?

Answer 10

Routing and IP, including fragmenting frames for network traversal.

Question 11

What type of address is used at the Network Layer? (Layer 3)

Answer 11

IP address.

Question 12

Which protocols operate at the Transport Layer? (Layer 4)

Answer 12

TCP (Transmission Control Protocol) and UDP (User Datagram Protocol).

Question 13

What does the Session Layer manage? (Layer 5)

Answer 13

Communication management between devices, including start, stop, and restart of sessions.

Question 13

What is the function of the Transport Layer? (Layer 4)

Answer 13

It manages transport of data, often referred to as the “post office” layer.

Question 14

What protocols are associated with the Session Layer? (Layer 5)

Answer 14

Control and Tunneling protocols

Question 15

What is the role of the Presentation Layer? (Layer 6)

Answer 15

Character encoding and application encryption (e.g., SSL/TLS).

Question 16

What Layer is the Presentation Layer (Layer 6) often combined with

Answer 16

The Application Layer.

Question 16

What is the Application Layer known for? (Layer 7)

Answer 16

It is the layer where users interact, involving protocols like HTTP, FTP, DNS, and POP3.

Question 17

What OSI layer corresponds to user-visible activity?

Answer 17

Layer 7 - Application Layer.

Question 18

What is an example of a function at Layer 6?

Answer 18

Application encryption like SSL/TLS.

Question 19

What type of data is managed at Layer 4?

Answer 19

TCP segments and UDP datagrams.

Question 20

What elements are associated with Layer 3?

Answer 20

IP addresses, routers, and packets.

Question 21

What does Layer 2 handle in terms of addressing?

Answer 21

MAC addresses and frames.

Question 22

What is an example of a real-world application for Layer 5 (Session Layer)?

Answer 22

Control protocols and tunneling protocols that manage the start, stop, and continuation of communication between devices.