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?
A.
Change Switch2 to switch port mode dynamic auto.
B.
Change the VTP domain to match on both switches.
C.
Change Switch1 to switch port mode dynamic auto.
D.
Change Switch1 to switch port mode dynamic desirable.
Data Traffic Blocked between VTP Domains
Sometimes it is required to connect to switches that belong to two different VTP domains. For example, there are two switches called Switch1 and Switch2. Switch1 belongs to VTP domain cisco1 and Switch2 belongs to VTP domain cisco2. When you configure trunk between these two switches with the Dynamic Trunk Negotiation (DTP), the trunk negotiation fails and the trunk between the switches does not form, because the DTP sends the VTP domain name in a DTP packet. Because of this, the data traffic does not pass between the switches.
https://www.cisco.com/c/en/us/support/docs/lan-switching/vtp/98155-tshoot-vlan.html#topic5
Selected Answer : B
Look at the answers
Trunk <--> Dynamic Desirable = Trunk (always)
so the negotiation mode has nothing to do with Trunk is not getting formed, it is something else.
and something else is the VTP domain.
This is what bothers me:
Error is reported on SW1 saying that G0/0 is not a trunk but received trunk BPDU from SW2.
That would make sense if SW1 G0/0 were dynamic but it is static Trunk, it doesn't need DTP from SW2 to make it trunk.
Now if the error was shown on SW2, that would make sense if VTP is required for DTP to be received. Without a valid DTP from the other side (from SW1), it would go to access mode.
If you are expecting trunk negotiation then both switch should belong to the same domain.
All proposed option offer dynamic mode and this will not work if both side do not belong to the same vtp domain.
unfortunately, I do not have this feature in my lab:
sw1(config-if)#switchport mode ?
access Set trunking mode to ACCESS unconditionally
dot1q-tunnel set trunking mode to TUNNEL unconditionally
trunk Set trunking mode to TRUNK unconditionally
sw1(config-if)#switchport mode
but I've played with changing the VTP domain name and this did not trigger an error from the question, I think this is a TRUNK issue, so we need to establish trunk here first ...
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