Question 4:OSPF Areas?

Answer:

BackBone Area:

The backbone area is area 0. It plays the role of the central node in the OSPF network and the link information of other areas is transmitted through area 0. so generally OSPF area consists of all networks in area ID 0.0.0.0 which are attached to the routing devices.
Standard Area:

In this type of area, OSPF packets can be normally transmitted and they can support up to 1,2,3,4, and 5 LSAs(Link State Advertisements). Ensure optimal routing since all routers know about all routes
Stub Area:

As the name defines this type of area does not accept external routes and does not accept the link information of the other routers outside the area. these areas do not receive type 4 or 5 LSAs from their ABRs(Area Border Router).
Totally stubby area:

These are completely stub areas same as sub-area this type of area does not accept external routes and does not accept the link information of the other routers outside the area. It should be noted here that since the default route is sent using Type 3 LSAs, the complete stub area does not allow ordinary Type 3 LSA packets, but it supports this type of LSA with default routes. This area supports Type 1, Type 2 LSAs, and Type 3 LSAs with default routes.
Not so Stubby area:  

It also has to send external routes to other areas. This area supports 1, 2, 3, and 7 LSAs. An NSSA makes use of type 7 LSAs.The functionality of NSSA is to designate a normal (stub) NSSA, all routers in the area must be so configured: This allows an ASBR to advertise external links to an ABR, which converts the type 7 LSAs into type 5 before flooding them to the rest of the OSPF domain.

Question 4:OSPF Areas?

Answer:

BackBone Area:

The backbone area is area 0. It plays the role of the central node in the OSPF network and the link information of other areas is transmitted through area 0. so generally OSPF area consists of all networks in area ID 0.0.0.0 which are attached to the routing devices.
Standard Area:

In this type of area, OSPF packets can be normally transmitted and they can support up to 1,2,3,4, and 5 LSAs(Link State Advertisements). Ensure optimal routing since all routers know about all routes
Stub Area:

As the name defines this type of area does not accept external routes and does not accept the link information of the other routers outside the area. these areas do not receive type 4 or 5 LSAs from their ABRs(Area Border Router).
Totally stubby area:

These are completely stub areas same as sub-area this type of area does not accept external routes and does not accept the link information of the other routers outside the area. It should be noted here that since the default route is sent using Type 3 LSAs, the complete stub area does not allow ordinary Type 3 LSA packets, but it supports this type of LSA with default routes. This area supports Type 1, Type 2 LSAs, and Type 3 LSAs with default routes.
Not so Stubby area:  

It also has to send external routes to other areas. This area supports 1, 2, 3, and 7 LSAs. An NSSA makes use of type 7 LSAs.The functionality of NSSA is to designate a normal (stub) NSSA, all routers in the area must be so configured: This allows an ASBR to advertise external links to an ABR, which converts the type 7 LSAs into type 5 before flooding them to the rest of the OSPF domain.