200-301 Question 196
Select 4A network administrator is configuring a trunk link between two switches using the 802.1Q protocol. After configuring the trunk, devices in VLAN 10 on Switch A are unable to communicate with devices in VLAN 10 on Switch B. Which of the following could be the cause of the issue?
- A
The native VLAN is mismatched on the trunk ports of both switches.
- B
802.1Q tagging is not enabled on one of the switches.
- C
The trunk port on one of the switches is configured as an access port.
- D
VLAN 10 is not allowed on the trunk link.
- E
The switches are using different 802.1Q tagging protocols.
Show answer and explanation
Correct answers: A, B, C, D
Explanation
802.1Q is the standard for VLAN tagging on Ethernet trunks. Issues such as mismatched native VLANs, lack of 802.1Q tagging, misconfiguration of trunk ports, or VLANs not being allowed on the trunk can prevent devices in the same VLAN from communicating across switches. However, 802.1Q does not have variations or different tagging protocols, so this option is incorrect.
- A. Correct.
If the native VLAN is mismatched, traffic from VLAN 10 might be interpreted incorrectly, leading to communication issues.
- B. Correct.
If 802.1Q tagging is not enabled on one of the switches, that switch will not process tagged traffic correctly, breaking inter-VLAN communication.
- C. Correct.
If one of the trunk ports is configured as an access port, it will not forward VLAN-tagged traffic, preventing VLAN 10 communication.
- D. Correct.
If VLAN 10 is not allowed on the trunk link, traffic for VLAN 10 will be dropped, preventing communication.
- E. Incorrect.
802.1Q is a standardized protocol, so the switches cannot use different 802.1Q tagging protocols. This option is invalid.