Final answer:
Drainstop is an administrative command for NLB clusters that allows servers to be removed from the load balancing rotation without dropping active connections, making it ideal for non-disruptive maintenance or updates.
Step-by-step explanation:
The Drainstop command is an option used for controlling Network Load Balancing (NLB) clusters. This command allows an administrator to gracefully remove a server from the cluster, preventing it from accepting new connections but still allowing it to continue serving current connections.
This is especially useful during maintenance windows or when you want to perform updates without disrupting service. The server will remain in this state until the administrator brings it back into the normal rotation with the NLB start command.