In large enterprise network supporting distribution routers with multiple interfaces, it’s always a tough task to keep track of adjacencies. There are times where you really wonder whether you want to form adjacencies with all interfaces or not.
The solution to this problem has been to configure the routing protocol on all interfaces and manually set the passive-interface command on the interfaces where adjacency was not desired. In some networks, this meant coding 200 or more passive interface statements. With the Default Passive Interface feature, this problem is solved by allowing all interfaces to be set as passive by default using a single passive-interface default command, then configuring individual interfaces where adjacencies are desired using the no passive-interface command
This feature was introduced with Cisco IOS v12.0. It works for all routing protocols that support the passive-interface command