Which status for VRRP routers is NOT valid?

The status of VRRP routers includes specific roles that they can play within the Virtual Router Redundancy Protocol framework. The valid statuses are "master" and "backup," which define the main operational states of VRRP routers. The "master" router is the one actively forwarding packets for the virtual router, while "backup" routers are on standby, ready to take over if the master fails.

"Transition" is not an officially recognized status within VRRP. Instead, the state transitions occur between the master and backup states when certain conditions are met, such as a failure detected on the master router.

Preemption, while a feature configured on VRRP routers, is not a status itself. It refers to the ability of a higher-priority backup router to take over the master role when it comes online or when the current master fails. This concept is vital for maintaining the best performance in a network, but it does not classify as a status that can be assigned to a router at any given time.

Therefore, since "preempt" does not represent an operational state within the VRRP protocol, it is the option that is not a valid status.