| 1. | Standard, stub, totally stubby, and NSSA. |
| 2. | All (standard, stub, totally stubby, and NSSA). |
| 3. | All except totally stubby. |
| 4. | Standard |
| 5. | Temporary LSA assigned to routes redistributed by an ASBR attached to an NSSA. |
| 6. | The only path out of the area is via a default route, which may be suboptimal should there be multiple exit points. |
| 7. | Minimizes the routing table and associated computations (SPF, event-driven changes). |
| 8. | Standard, non-backbone areas. |
| 9. | All internal routers in a stub area must have this same command so that all hellos agree on the stub area flag. |
| 10. | Null indicates no authentication, plaintext means that the password can be read with the aid of a protocol capture tool, and MD5 authentication uses a key number in combination with a password to create a hash value that is not decipherable if captured on the network. |
| 11. | A message digest is a hash value used to secure a password. |
| 12. | N1 or N2 |
