Exam 300-420 topic 1 question 205 discussion

Actual exam question from Cisco's 300-420

Question #: 205
Topic #: 1

Refer to the exhibit. A network engineer with an employee ID: 4433:77:420 must design a BGP solution based on these conditions:
• Traffic sessions occur between the branches and the data center.
• Branch B has limited resources to process routing updates.
• HQ must filter out all prefixes from branch A to R4.

Which outbound route filtering (ORF) solution must the engineer choose?

A. Use a prefix list with the 10.10.10.0/24 subnet for ORF on R5.
B. Use a prefix list with the 10.10.10.0/24 subnet for ORF on R2
C. Use a prefix list with the 192.168.10.0/24 subnet for ORF on R2.
D. Use a prefix list with the 192.168.10.0/24 subnet for ORF on R4.

Show Suggested Answer

Suggested Answer: B 🗳️

by cerifyme85 at April 19, 2023, 5:32 a.m.

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neiker45

1 year ago

ORF will send messages to the other side asking for only the exact prefixes that are set up on the side that has set up ORF. Here's a good link for that: https://ine.com/blog/2008-05-05-understanding-bgp-outbound-route-filtering-bgp-orf

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TheGorn

1 year ago

So according to that document only the routes that are needed by Branch B should be in the ORF config of R2. Not the router that is supposed to be filtered out, and not the route that Branch B is. So that would eliminate all of the choices in the question from being correct. It would then be an ORF on R2 with 172.16.10.0/24 set as the advertised route...

upvoted 1 times