CPNT 217 Data link layer

Question 1

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

Answer 1

layer 2. node-to-node data transfer and enabling reliable communication between directly connected devices on the same network

Question 2

What are the main functions of the Data Link Layer?

Answer 2

Framing: Packages raw bits into frames for easier handling. Error Detection: Identifies and corrects errors in transmitted data. Flow Control: Manages data flow to prevent congestion. MAC Addressing: Uses unique addresses to identify devices on a network.

Question 3

What are the two sublayers of the Data Link Layer?

Answer 3

Logical Link Control (LLC) and Media Access Control (MAC).

Question 4

What does the Logical Link Control (LLC) sublayer do?

Answer 4

Communicates between networking software at higher layers and device hardware.
multiplexing
flow control
error detection

Question 5

What is the primary protocol used at Layer 2?

Answer 5

Ethernet is the default protocol at Layer 2.

Question 6

What is a frame in the context of the Data Link Layer?

Answer 6

A frame is the Protocol Data Unit (PDU) at Layer 2
created by encapsulating packets from the Network Layer with control information

Question 7

What is included in a frame header?

Answer 7

Data Link Header

Question 8

What is the purpose of the frame trailer?

Answer 8

Usually contains error-checking information and is optional.

Question 9

What is a MAC address?

Answer 9

A unique 48-bit address assigned to each Network Interface Card (NIC)

Question 10

What are the three types of MAC addresses?

Answer 10

Unicast (single device) multicast (device group) broadcast (all devices)

Question 11

What is a unicast MAC address?

Answer 11

An address that points to a single NIC

Question 12

What is a broadcast MAC address?

Answer 12

An address that allows all hosts on the network to receive the frame

Question 13

What does the term ‘network topology’ refer to?

Answer 13

arrangement of devices (nodes) and connections (links) in a computer network

Question 14

What are the two types of network topology?

Answer 14

Physical topology and logical topology.

Question 15

What is a bus topology?

Answer 15

A network topology where each node connects to a common media.

Question 16

What is a star topology?

Answer 16

A network topology where each node connects to a central point

Question 17

What is a mesh topology?

Answer 17

A network topology where each node is connected to every other node (full mesh) or only to select nodes (partial mesh).

Question 18

What is the role of switches in a network?

Answer 18

Switches use a MAC address table to forward frames to specific devices

Question 19

What is a collision domain?

Answer 19

A segment of a network where data packets can collide

Question 20

How do switches reduce collisions?

Answer 20

By sending frames only to the port where the destination MAC address is attached

Question 21

What is a MAC address table?

Answer 21

A table that maps MAC addresses to switch ports

Question 22

What are the common switch form factors?

Answer 22

Fixed, rack mounted and stackable

Question 23

What is the purpose of data encapsulation in networking?

Answer 23

To package data with necessary protocol information for transmission across the network.

Question 24

What is the significance of error detection in frames?

Answer 24

To ensure data integrity by identifying and correcting errors during transmission.

Question 25

What is the function of the Organizationally Unique Identifier (OUI) in a MAC address?

Answer 25

A 24-bit identifier assigned to a specific manufacturer/model by the IEEE.