Full Version: QID:NE35 seems incorrect
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Answer ==>  If RIPv1 is configured on all routers, then RTC will receive updates about RTA LAN. (SHOULD NOT BE INCLUDED AS CORRECT ANSWER)

RTA will never send updates about its local LAN since RTA is configured as:

RTA(config-router)#passive-interface e0 (IT WILL NOT SEND LOCAL LAN)


The question seems perfectly correct to me.  Maybe you should re-read the section in you book about exactly what the passive-interface command under RIP does.  To quote the Authorized Self-Study Guide, Building Scalable Cisco Internetworks (BSCI), Third Edition, "When you us the passive-interface command with RIP and IGRP, routing updates are not sent out of the specified interface.  However, the router still receives rotuing update on that interface."

In this questions scenario, updates are being sent out of the serial interface, while the passive-interface command was applied to the ethernet interface.


I agree with that principle: passive interface will not send but receive updates:
As you can see:

RTA e0 is configured as passive interface, so it will not send updates but it will receive updates.

How can RTC receive updates about RTA e0 while RTA e0 interface is configured as passive-interface? (will not send update about e0)

Please look very carefully to the exhibit. I think the answer in NE35 is incorrect, there are only 2 answers.



RTA e0 has nothing to do with RIP updates to RTC. RTA e0 is a LAN interface and is not connected to any other router and RIP can be disabled on that interface. RTA uses s0 to advertise routes to neighboring router RTB, including the network on e0. If the passive-interface command was used on the RTA s0 interface, then you would be correct. There's no passive-interface command on s0, so RTA will advertise routes out s0 to RTB s0/0. RTB will advertise those same routes out s0/1 to RTC since it too has no passive-interface command set. RTC will receive that update via its s1 interface since the passive-interface command still allows updates to be received. So, there's the path from the e0 network on RTA getting to RTC's routing table.