When would you typically use the command 'spanning-tree portfast trunk'?

The command 'spanning-tree portfast trunk' is typically used on interfaces connecting to a single endpoint, such as a server, because it enables PortFast on a trunk interface without introducing delays that are usually present in the Spanning Tree Protocol (STP) when a port transitions through its states (listening and learning) to become active.

When an interface is configured with PortFast, it immediately transitions into the forwarding state, which is beneficial when connecting devices that are not part of a network topology, such as end-user devices or servers. This helps in reducing the time it takes for the connected devices to communicate on the network, as they will not have to wait for the STP convergence process to complete.

In contrast, using PortFast on interfaces connecting to another switch or interfaces requiring additional STP protection is not typically recommended, as these links are crucial parts of the network topology that may require normal STP functionality to prevent loops. Similarly, applying PortFast indiscriminately to all access ports could lead to network instability, especially if any of those ports connect to devices capable of causing a loop.