Define VLAN trunking and the purpose of 802.1Q tagging.

Define VLAN trunking and the purpose of 802.1Q tagging.

• A. VLAN trunking isolates VLANs on separate switches.
• B. VLAN trunking carries traffic for multiple VLANs over a single physical link; 802.1Q tags frames to indicate VLAN membership.
• C. 802.1Q tagging encrypts wireless frames.
• D. 802.1Q tagging is used to identify the physical port number.

Answer: (B)

VLAN trunking allows a single physical link to carry traffic for multiple VLANs, with 802.1Q tagging marking frames to indicate their VLAN membership. This tagging lets the receiving switch know which VLAN a frame belongs to so it can place it into the correct broadcast domain. On trunk ports, frames from many VLANs are sent over one cable, each frame carrying a VLAN ID. On access ports, frames typically travel untagged and belong to one VLAN, but when they traverse a trunk, they get tagged for the correct VLAN. This combination enables scalable network designs where switches can communicate many VLANs over fewer physical connections. The other ideas don’t fit because 802.1Q tagging is not encryption, it’s a way to identify VLAN membership, and trunking is not about isolating VLANs on separate switches by itself but about carrying multiple VLANs over a single link. It also isn’t about identifying a physical port number.

VLAN trunking allows a single physical link to carry traffic for multiple VLANs, with 802.1Q tagging marking frames to indicate their VLAN membership. This tagging lets the receiving switch know which VLAN a frame belongs to so it can place it into the correct broadcast domain. On trunk ports, frames from many VLANs are sent over one cable, each frame carrying a VLAN ID. On access ports, frames typically travel untagged and belong to one VLAN, but when they traverse a trunk, they get tagged for the correct VLAN. This combination enables scalable network designs where switches can communicate many VLANs over fewer physical connections.

The other ideas don’t fit because 802.1Q tagging is not encryption, it’s a way to identify VLAN membership, and trunking is not about isolating VLANs on separate switches by itself but about carrying multiple VLANs over a single link. It also isn’t about identifying a physical port number.