Two engineers at a rural cooperative's NOC both try to enter configuration mode on the same router during a maintenance window, and the second one wants to guarantee that no one else's edits get mixed into theirs while working on a sensitive routing-policy change. Which approach gives that engineer sole, exclusive editing rights to the candidate configuration?

Entering configuration mode with configure exclusive locks the entire candidate configuration to that single user's session; any other user who tries to enter configuration mode is told the configuration is currently locked and by whom, preventing a second engineer's simultaneous edits from ever mixing into the same candidate during a sensitive change. Plain configure enters configuration mode in the normal, shared mode, where every logged-in user is editing the same candidate configuration at once, which is the opposite of the sole-access guarantee the engineer needs here. configure private gives each user an independent, isolated copy of the candidate to edit, with changes merged together only at commit time — useful for letting multiple engineers work in parallel without stepping on each other, but it doesn't freeze everyone else out of editing entirely the way exclusive access does. commit synchronize applies to routers with dual routing engines, ensuring both engines' configurations commit together, and has nothing to do with locking editing access among users. Caveat: an exclusive lock is released only when that user exits configuration mode, so it should be released promptly once the sensitive change is committed so the router isn't left inaccessible to other legitimate work. Check: have the other engineer attempt configure and confirm they receive a message that the configuration database is already exclusively locked.