What state does a port enter when it is administratively down?

When a port is administratively down, it enters the Disabled state. This state indicates that the port has been manually disabled by the network administrator, effectively preventing all traffic from passing through that port. In this state, the port does not participate in any Spanning Tree Protocol (STP) activities, and it is not available for use in the network until it is re-enabled by an administrator.

The Disabled state is critical in network management as it allows an administrator to control and configure ports selectively, ensuring that only specific ports are active or inactive based on network requirements or troubleshooting needs. When a port is disabled, it does not transition through the states of Blocking, Listening, or Learning, which are part of the normal STP processes for managing traffic and preventing loops in an active port state.