Which statement about 802.1Q tagging and trunk ports is correct?

• A. It tags frames for individual VLANs on access ports only.
• B. It defines the tagging standard between devices on a single VLAN.
• C. It is a protocol for resolving IP to MAC.
• D. 802.1Q tagging is used to carry multiple VLANs using tagging on trunk ports.

Answer: (D)

802.1Q tagging lets a single Ethernet frame carry information about which VLAN it belongs to by inserting a VLAN tag into the frame. On a trunk link between switches, this tag allows traffic from many VLANs to traverse the same physical connection while staying separated by VLAN. Access ports, in contrast, handle frames for only one VLAN and usually send/receive untagged frames, which is why tagging on access ports isn’t the right description. ARP is a separate function for mapping IP to MAC, not VLAN tagging. The purpose of 802.1Q is precisely to carry multiple VLANs over trunk ports using tagging, making that statement correct.