Today we noticed there was a failure with our backups on an exchange 2003 server using Replication Manager for Exchange. It appears that the application talks on 6543 and the port was in use. When I perform a netstat -n we see the following. <IP Address of the Exchange Server>:6543 <IP Address of a DC>:3268 ESTABLISHED It looks like GC lookups are reserving this port. If we go ahead and reserve the port for Replication Manager, will GC lookups use a new random free port on the box, or will be break something. Thanks

It should be ok.