CompTIA Network+ (N10-009)Network ImplementationEasy
A network technician is configuring a switch trunk link that will carry traffic for VLANs 10, 20, and 30 between two switches. Which protocol should the technician enable on the trunk port to tag frames with their VLAN membership as they cross the link?
- A802.1Q
- B802.1X
- C802.3af
- D802.11ac
Show answer & explanationAnswer & explanation
Correct answer: A. 802.1Q
IEEE 802.1Q is the standard for VLAN tagging, inserting a 4-byte tag into Ethernet frames so switches can identify VLAN membership across trunk links. 802.1X is for port-based authentication, 802.3af is Power over Ethernet, and 802.11ac is a wireless standard.
Why the other options are wrong
- B. 802.1X is for network access authentication, not VLAN tagging.
- C. 802.3af is a PoE standard, unrelated to VLAN tagging.
- D. 802.11ac is a Wi-Fi standard, not applicable to wired trunking.
802.1Q Trunking
IEEE standard that inserts a VLAN tag into Ethernet frames so multiple VLANs can traverse a single trunk link between switches.
- Adds a 4-byte tag containing the VLAN ID
- Supports up to 4094 VLAN IDs
- Native VLAN traffic is sent untagged by default
Memory trick: 'Q' for Queue-up tags on the trunk highway.