Two routers are trying to establish an OSPFv3 adjacency over an Ethernet link, but the adjacency
is not forming. Which two options are possible reasons that prevent OSPFv3 to form between
these two routers? (Choose two.)
A.
mismatch of subnet masks
B.
mismatch of network types
C.
mismatch of authentication types
D.
mismatch of instance IDs
E.
mismatch of area types
I don’t agree and can’t find a reference to confirm it, to my mind it has to be B, C and E…
A) The question says that routers are trying to establish the adjacency so I conclude that they are able to reach each other. According to this, subnet configuration is OK.
B) Network type: point to point, NBMA network… is not a requiremt to form neighbors.
C) It says “authentication TYPES”, it means, no authentication, plain password or IPSEC. This is a tricky answer but the key here is the word TYPES.
D) You can specify instance inside an OSPFv3 proccess. In order to create an adjacency instances ID have to match. That’s a correct answer.
E) Area types: STUB, NSSA… they have to be the same to form an adjacency so it’s correct.