Data link layer

Question 1

What is the Data Link Layer in the OSI Reference Model?

Answer 1

Layer 2 of the OSI Reference Model

The OSI model consists of 7 layers, with the Data Link Layer being the second layer, responsible for node-to-node data transfer.

Question 2

What are some protocols used at Layer 2?

Answer 2

• Ethernet
• Frame Relay
• High-Level Data Link Control (HDLC)
• Multi-Protocol Label Switching (MPLS)
• Others

Ethernet is the default protocol at Layer 2.

Question 3

What is the main function of the Data Link Layer?

Answer 3

Forwards frames using MAC Addresses

The Data Link Layer is responsible for the delivery of frames between devices on the same network.

Question 4

What does the Data Link Layer frame structure consist of?

Answer 4

• Frame Header
• Payload
• Frame Trailer

The payload usually contains upper-layer data and may include control information for the Layer 2 protocol.

Question 5

What is a MAC Address?

Answer 5

A unique 48-bit address in hexadecimal assigned to every Network Interface Card (NIC)

MAC addresses are also known as physical addresses and are burned into the hardware.

Question 6

What are the two sections of a MAC Address?

Answer 6

• OUI – Organizationally Unique Identifier (24 bits)
• Vendor Assigned ID (24 bits)

The OUI is assigned by the IEEE to a specific manufacturer.

Question 7

What types of MAC addresses exist?

Answer 7

• Unicast Addresses
• Broadcast Addresses
• Multicast Addresses

Each type has different addressing rules and purposes in a network.

Question 8

What is the difference between Physical Topology and Logical Topology?

Answer 8

• Physical Topology: How devices are physically connected
• Logical Topology: How devices communicate inside the network

Understanding both topologies is crucial for network design.

Question 9

What are common network topologies?

Answer 9

• Bus
• Ring
• Star
• Mesh

Each topology has its own advantages and disadvantages in terms of performance and reliability.

Question 10

What is a collision domain?

Answer 10

A media segment where collisions can occur

Hubs create a single collision domain, while switches break up collision domains.

Question 11

How do switches differ from hubs in frame forwarding?

Answer 11

Switches forward frames to specific devices using a MAC address table, while hubs broadcast frames to all ports

This makes switches more efficient and reduces collisions.

Question 12

What is the purpose of a switch MAC Address Table?

Answer 12

Tracks which MAC address is connected to each switchport

The table is updated over time to ensure accuracy in frame forwarding.

Question 13

What are the sublayers of the Data Link Layer?

Answer 13

• Logical Link Control
• Media Access Control

These sublayers handle different aspects of data link layer functions.

Question 14

Fill in the blank: The Data Link Layer uses _______ as its Protocol Data Unit (PDU).

Answer 14

Frame

The frame is the data format used by the Data Link Layer.

Question 15

True or False: A switch operates in full-duplex mode, allowing send and receive simultaneously.

Answer 15

True

This is one of the advantages of using switches over hubs.

Question 16

What are the forms of switch form factors?

Answer 16

• Fixed Form
• Chassis
• Stackable

Different form factors cater to various network needs.