Couple Questions

bankintheroll

I just finished watching the Exam Walkthrough vids for CCENT on CBTNuggets. I had a couple questions.

1) Here is the question and highlighted answers:



I'm wondering how answer B is correct? Would it be because R6 is directly connected to R5 and could telnet to that router. Then telnet to R2, then to R1? I thought you would need some kind of routing defined, but I'm guessing that is how it's done.

I thought C was right, which states there would be 3 routers with 3 equal cost routes in their respective routing tables. Wouldn't R1, R4, and R6 have equal cost routes?



2) Here is the question and highlighted answer:



Why is B correct? I didn't think OSPF worked on hops, which is what the cost of 4 refers to, right? I thought the answer was C, because OSPF has an AD of 110. Where am I wrong here?

Thanks in advance.

EdTheLad

1) You don't need routing to telnet to the same subnet, i.e. the directly connected ip address of neighbor. To have 3 equal cost routes to a prefix you need 3 next-hop neighbors directly connected i.e. R1,R4 and R6 all have one neighbor so there can only be one next-hop route in the rib.

2) Silly question, as you have to assume the auto-cost bandwidth is default. Read how ospf calculates cost using bandwidth and you will understand this.