CCNP Architecture Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✓

  Type 1, Type 2, Type 3 (including default)

  Why this is correct

  In a totally stubby area, the ABR suppresses Type 4 (ASBR-summary) and Type 5 (AS-external) LSAs, and also replaces all Type 3 inter-area summaries with a single default route. This leaves only Type 1 (router) and Type 2 (network) LSAs for intra-area topology, plus the injected Type 3 default LSA for any traffic leaving the area. Therefore, the allowed LSA set is exactly Type 1, Type 2, and the default Type 3.

• ✗

  Type 1, Type 2, Type 3, Type 5

  Why it's wrong here

  Type 5 LSAs advertise routes from outside the OSPF autonomous system, such as redistributed static or RIP routes. Both stubby and totally stubby areas filter these external LSAs to reduce routing table size and prevent external route flapping from affecting internal routers. Since a totally stubby area blocks all Type 5 LSAs, listing Type 5 in the allowed set is factually wrong.

• ✗

  Type 1, Type 2, Type 4, Type 5

  Why it's wrong here

  Type 4 LSAs are generated by ABRs to advertise the location of an ASBR to other areas, and Type 5 LSAs carry the actual external routes. A totally stubby area prevents external routes from being learned, which also makes Type 4 LSAs irrelevant because there is no ASBR reachability to advertise. Both Type 4 and Type 5 are filtered at the ABR, so an option that includes either is incorrect.

• ✗

  Type 1, Type 2, Type 3 (including default), Type 4

  Why it's wrong here

  Although a totally stubby area does permit Type 1, Type 2, and a default Type 3 LSA, it explicitly blocks Type 4 LSAs. The ABR does not forward ASBR-summary LSAs into a totally stubby area, even though it injects the default inter-area route. Including Type 4 in the allowed LSA list is therefore inaccurate; only the default Type 3 summary is permitted as the sole inter-area route.