Which statement is correct about 802.1Q trunking?

A.
Both switches must be in the same VTP domain.

B.
The encapsulation type of both ends of the trunk does not have to match.

C.
The native VLAN on both ends of the trunk must be VLAN 1.

D.
802.1Q trunking can only be configured on a Layer 2 port.

E.
In 802.1Q trunking, all VLAN packets are tagged on the trunk link, except the native VLAN.

Explanation:

E is correct because, "frames from the native VLAN of an 802.1Q trunk are not tagged with the VLAN number."
Incorrect Answers:
A: This is true for VTP information to be propagated, but it is not necessary for two switches to be trunked together.
B: This is incorrect because the encapsulations types do have to match or it won’t work properly. You can’t use 802.1Q on one side and ISL on the other. C is incorrect because the native VLAN doesn’t necessarily have to be VLAN 1.
C: By default, the native VLAN is VLAN 1 but this can be effectively changed to a different VLAN and the trunk will still be functional.
D: Trunks can be established with router interfaces using sub-interfaces, which are layer 3.
Reference: http://www.cisco.com/warp/public/473/27.html