Exam 300-420 topic 1 question 29 discussion

I this correct answer is C.

Btw, there are STUB areas, STUBBY areas do not exist (if it does, I cannot find it on Cisco documentation).

Ans: D A stubby area in OSPF is used to reduce router resource utilization and limit the size of the routing table while still allowing for full connectivity to the rest of the OSPF network. This choice is appropriate when you have no demand for traffic to pass through the area, as it blocks the type 5 external LSAs, thereby reducing the routing information and resources required in that specific area.

The provided answer is correct the answer is D. - Stub Area will be able to talk to the rest of the network (This is a requirement) where as the TSA can't. - The WAN router IS NOT an ASBR, it is simply an ABR connected to the rest of the OSPF Network, it would of been an ASBR if EIGRP or a different routing protocol was running here. - Stub area also uses low resources, o tho TSA uses less but unfortunately it does not mee the (needs to reach the rest of the network requirement) where as Stubby Area does.

D is Correct

we need ASBR for WAN, and stub area does not have ASBR

C is better answer than D. A stub area is an area in which advertisements of external routes are not allowed, reducing the size of the database. A totally stubby area (TSA) is a stub area in which summary link-state advertisement (type 3 LSAs) are not sent. A default summary LSA, with a prefix of 0.0.

C correct

totally stubby area inject 1 default route into the area, it should able to connect rest of the network with minimal resource used

“There is no demand for traffic to pass through this area.” So we know from this that an NSSA or a totally not so stubby area is needed. NSSA’s or totally NSSA’s are only needed if routes are being injected into the OSPF domain. So A and B are not correct. C and D are both similar in that they both do not inject Type 5 LSA, which would keep router utilization down. However, if we desire to cut down on as many LSA’s as possible, which would then cut down on the router utilization due to the OSPF routers not having to run the SPF calculation, then answer C is MOST correct. A totally stubby area restricts not only type 5, but also type 4 and type 3 LSA’s. Since the requirement states “provide minimal resource utilization” answer C “totally stubby area” is correct.

I think C - Totally Stubby Area is correct. Just a default into this new area is fine.

Why not A?

I think C as LSA type1 + type2 + Defaut required to minimise Router resources utilization -> total stub area

Sorry. Answer should be C as Stub area blocks external traffic

D is answer

Answer is right D, 2 routers, means Layer 3 LSA's need to get in so the area knows how to reach routes on the LAN/ other Areas.

A totally stubby area is an area that is not able to accept LSA type 3 or 5 which contain routes from outside the OSPF domain and is not able to accept routes from outside the area; traffic is only able to exit the area via a default route (which is injected via the ABR).Jan 18, 2012