Cisco CCNA Basic Switching Concepts Questions and Answers

Question 1

A switch receives a frame on its Fa0/1 interface. The source MAC address is 0000.aaaa.aaaa and the destination MAC address is 0000.bbbb.bbbb. The switch has no entry for 0000.bbbb.bbbb in its MAC address table. What action will the switch take?

Accepted Answer

Forward the frame out of all interfaces except the originating port, Fa0/1.

Answer

When a switch receives a unicast frame with a destination MAC address that is not in its MAC address table, it floods the frame to all ports within the same VLAN except for the port on which it was received. This process is known as unknown unicast flooding. The switch also learns the source MAC address (0000.aaaa.aaaa) and associates it with the incoming port (Fa0/1).

Question 2

Which of the following is a primary benefit of using VLANs in a network?

Accepted Answer

To segment the network into multiple broadcast domains.

Answer

Virtual LANs (VLANs) are used to logically segment a Layer 2 network. Each VLAN is a separate broadcast domain. This means that broadcast frames sent by a device in one VLAN are only forwarded to other devices within that same VLAN, not to the entire physical network. This improves security, reduces unnecessary traffic, and enhances network performance.

Question 3

A network administrator is concerned about network latency and wants to ensure frames with errors are not propagated through the network. Which switching method should be used?

Accepted Answer

Store-and-Forward

Answer

The store-and-forward switching method receives the entire frame before making a forwarding decision. This allows the switch to check the Frame Check Sequence (FCS) at the end of the frame for errors. If an error is detected, the frame is dropped. Cut-through methods, like fast-forward and fragment-free, begin forwarding before the entire frame is received and therefore cannot check for all errors.

Question 4

In a switched network, how does a switch populate its MAC address table?

Accepted Answer

By examining the source MAC address of incoming frames.

Answer

A switch learns the MAC addresses of connected devices dynamically by inspecting the source MAC address of every frame it receives. It then creates an entry in its MAC address table, associating the source MAC address with the interface on which the frame was received.

Question 5

A network consists of a single 24-port switch. All ports are operating in full-duplex mode. How many collision domains and broadcast domains exist in this network by default?

Accepted Answer

24 collision domains, 1 broadcast domain

Answer

Each port on a switch is a separate collision domain. Therefore, a 24-port switch has 24 collision domains. By default, all ports on a single switch are part of the same broadcast domain (typically VLAN 1). Broadcasts are forwarded out of all ports. Routers or VLANs are required to segment a network into multiple broadcast domains.

Cisco CCNA Practice Test

Cisco CCNA Practice Test

Cisco CCNA Basic Switching Concepts Questions and Answers