How should VLAN tagging from host be validated if hardware offloads VLAN tagging?

• A. Rely on switch port logs to validate VLAN tagging.
• B. Verify VLAN tagging by inspecting the host's OS network interface configuration.
• C. Check 802.1Q tags only by reading the NIC driver documentation.
• D. Capture with tcpdump -i <iface> -vvv and check 802.1Q tags (if not offloaded).

Answer: (D)

To validate VLAN tagging, you need to see the actual frames as they are transmitted. Run a packet capture on the host interface with verbose decoding and inspect the 802.1Q tag field. This shows whether the frames carry the expected VLAN tag. If the NIC is offloading VLAN tagging, the host capture may not display the tag because tagging is done in hardware; in that case you’ll either disable offloading to verify on the host or capture at a point where the tag is preserved (such as on the switch). This direct inspection of the frame tags on the wire is the reliable way to confirm VLAN tagging behavior.