Common Cisco VTP Troubleshooting Issues

1- Different domain. A switch must has the same domain name in order to participate
Example

S1(config)#vtp domain NOukgoodbye
Changing VTP domain name from ukgoodbye to NOukgoodbye
S1(config)#vtp mode cl01:06:12 %DTP-5-DOMAINMISMATCH: Unable to perform trunk negotiation on port Fa0/24 because of VTP domain mismatch.

i01:06:13 %DTP-5-DOMAINMISMATCH: Unable to perform trunk negotiation on port Fa0/2 because of VTP domain mismatch.

2- Trunk between the switches,
The VLAN Trunking protocol, is Cisco proprietary protocol, as its name says “Trunking”
VLAN Trunking protocol

To be a trunk to be form between two switches is required

3- VTP version

4- VTP password