(06-18-2020, 11:23 PM)lodgeg Wrote: (QID:AN110) Refer to the exhibit. A router received five routes from different routing information sources. Which two routes does the router install in its routing table? (Choose two)
Exhibit - How2Pass.com
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iBGP route 10.0.0.0/30
RIP route 10.0.0.0/30
OSPF route 10.0.0.0/16
OSPF route 10.0.0.0/30
EIGRP route 10.0.0.1/32
How2Pass Answers:
OSPF route 10.0.0.0/16
EIGRP route 10.0.0.1/32
Shouldn't the correct answers be EIGRP 10.0.0.1/32 and OSPF route 10.0.0.0/30 due to the longest prefix rule?
I believe that the answer How2Pass chose is predicated on having the /16 route and the /30 routes pointing to the same next hop destination. If that were the case then the /16 route would efficiently summarize those four routes. This is an ambiguity not addressed in the question, however if there are only 2 correct answers this would be the only case that makes sense.
If the /16 and /30 routes pointed to different next hop destinations, then the router would install three routes in its routing table, which would be OSPF route 10.0.0.0/16, EIGRP route 10.0.0.1/32, and one of the /30 routes depending on the next hop destination(s). If you were to just compare the /30s without any other information present, OSPF has the lowest AD value.
The wording that the routes came from "different routing information sources" definitely makes this confusing and I was similarly frustrated. Based on the information present in the question I would chose H2P's answer on the test, but if someone were to provide a more definitive answer I would be grateful.