Refer to the exhibit. An engineer implemented several configuration changes and receives the logging message on switch1. Which action should the engineer take to resolve this issue?

Question

Exhibits

Options

• AChange the VTP domain to match on both switches
• BChange Switch2 to switch port mode dynamic auto
• CChange Switch1 to switch port mode dynamic auto
• DChange Switch1 to switch port mode dynamic desirable

• A
  89% (17)
• C
  5% (1)
• D
  5% (1)

Explanation

Explanation

Option A is correct because the logging message on Switch1 indicates a VTP domain mismatch - when two switches attempt to form a trunk link, they exchange VTP advertisements, and if the VTP domain names do not match (and neither is in the null/default domain), the trunk will not pass VLAN information correctly, causing the error seen. Aligning the VTP domain name on both switches resolves this synchronization issue and allows the trunk to function properly.

Why the distractors are wrong:

• B & C are incorrect because changing a port to dynamic auto makes it passively wait for the other end to initiate trunking; this does not address a VTP domain mismatch and could actually prevent trunk formation altogether.
• D is incorrect because dynamic desirable actively tries to negotiate a trunk, which may already be configured, but it still won't fix an underlying VTP domain name conflict.

Memory Tip

Think of VTP domains like area codes - even if two phones (switches) are connected, they can't communicate properly without matching area codes. If you see a trunk-related VTP error in a logging message, always check the domain name first before touching port modes.

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