CompTIA Network+ Network+ Ethernet Switching and VLANs 2

Question 1

A switch receives a frame destined for a MAC address not in its CAM table. What does it do?

Accepted Answer

Floods the frame out all ports except the receiving port

Answer

When a switch cannot find a destination MAC in its CAM table, it floods the frame out all ports except the one it arrived on — this is called unknown unicast flooding.

Question 2

Which IEEE standard defines the 802.1Q VLAN tagging mechanism?

Accepted Answer

IEEE 802.1Q

Answer

IEEE 802.1Q defines the standard for VLAN tagging, inserting a 4-byte tag into Ethernet frames to carry VLAN membership information across trunk links.

Question 3

What is the size of the VLAN ID field in an 802.1Q tag?

Accepted Answer

12 bits

Answer

The 802.1Q VLAN ID field is 12 bits, supporting VLAN IDs from 0 to 4095 (4,096 possible VLANs).

Question 4

A port configured as an access port receives a frame with an 802.1Q tag. What should a properly configured switch do?

Accepted Answer

Drop the frame

Answer

Access ports expect untagged frames; a tagged frame arriving on an access port is typically dropped as it indicates a misconfiguration or security issue.

Question 5

Which spanning tree port state allows a port to learn MAC addresses but NOT forward user traffic?

Accepted Answer

Learning

Answer

The Learning state allows the switch to populate its MAC address table from incoming frames but does not yet forward user data traffic.

CompTIA Practice Test

CompTIA Practice Test

CompTIA Network+ Network+ Ethernet Switching and VLANs 2