Exam 300-410 topic 1 question 266 discussion

Actual exam question from Cisco's 300-410

Question #: 266
Topic #: 1

Refer to the exhibit. A prefix list is created to filter routes inbound to an EIGRP process except for network 10 prefixes. After the prefix list is applied, no network 10 prefixes are visible in the routing table from EIGRP. Which configuration resolves the issue?

A. ip prefix-list EIGRP seq 10 permit 0.0.0.0/0 le 32
B. ip prefix-list EIGRP seq 20 permit 10.0.0.0/8 ge 9 ip prefix-list EIGRP seq 10 permit 0.0.0.0/0 le 32
C. ip prefix-list EIGRP seq 20 permit 10.0.0.0/8 ge 9
D. ip prefix-list EIGRP seq 5 permit 10.0.0.0/8 ge 9 no ip prefix-list EIGRP seq 20 permit 10.0.0.0/8

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Suggested Answer: D 🗳️

by HungarianDish_111 at May 12, 2023, 12:10 p.m.

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HungarianDish_111

Highly Voted 2 years ago

Selected Answer: D

"ip prefix-list EIGRP seq 5 permit 10.0.0.0/8" is correct. A prefix-list is an ordered list. "permit 10.0.0.0/8" needs to come before "deny 0.0.0.0/0 le 32" (deny everything), otherwise the "10" network is matched by the deny statement and thus, it gets to be filtered. "sequence 5" places the "permit 10.0.0.0/8" before "deny 0.0.0.0/0 le 32".

upvoted 6 times

HungarianDish_111

2 years ago

https://networklessons.com/eigrp/how-to-configure-prefix-list-on-cisco-router

upvoted 1 times

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[Removed]

1 year, 9 months ago

To add to this answer, the second problem resolved in answer D is the acceptance of prefix lengths greater than /8. As it stood, sequence 20 was only accepting the prefix "10.0.0.0/8" and nothing else. The keyword "ge 9" allows the prefix statement to accept prefix lengths between /8 and /32. Alternatively it could have been "le 32"

upvoted 2 times

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[Removed]

Most Recent 10 months ago

Selected Answer: D

D is corerct

upvoted 1 times

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