Which VTP mode is set as the default in VTP version-3?

In VTP version 3, the default mode is VTP Server. This means that when a Cisco switch is configured to use VTP version 3, it will operate in server mode by default unless otherwise specified. VTP Server mode allows the switch to create, modify, and delete VLANs for the entire VTP domain and to propagate VLAN information to other switches in the domain.

VTP version 3 brings several enhancements over previous versions, including support for additional features like enhanced security measures and support for extended VLANs. However, the core functionality remains consistent with the notion that the server mode is the primary means by which VLAN information is managed and distributed.

Understanding this default behavior is fundamental for designing and troubleshooting VTP in a network environment, as it impacts how VLAN changes are communicated and managed across a network of switches.