Implement Cisco IOS routing features
These questions are derived from the Self Test Software Practice Test for Cisco exam #642-901 – Building Scalable Cisco Internetworks
Objective: Implement Cisco IOS routing features
SubObjective: Describe, configure or verify route filtering (i.e., distribute-lists and passive interfaces)
Single Answer, Multiple Choice
Which method should you use to block all routing updates from being sent into a network through an interface?
- Static route
- Default route
- Passive interface
- Route-update filtering
C Passive interface
To stop all outbound routing updates from an interface, you can use the passive-interface command. Although routing updates and hellos will not be sent on the interface, the network tied to that interface will still be advertised through the routing protocol.
There are numerous reasons to use the passive-interface command. For instance, suppose that you have a LAN with only end hosts on it and no other router. Additionally, there is no reason to send EIGRP packets, but you want EIGRP to advertise that that network can be reached. The combination of a network statement for that interface plus a passive-interface command would be appropriate.
Route-update filtering can block all routing updates if you prefer, but it is really intended for selective filtering of updates. If your goal is to block all updates, the passive-interface command is best.
Default routes and static routes can be used as ways around having to send routing updates out an interface. However, if your goal is to block updates, you should issue the passive-interface command.
Building Scalable Cisco Internetworks – Manipulating Routing Updates