Section 1.6 - OSPF Special Area Types

Question 1

What are the characteristics of a stubby area in OSPF?

Answer 1

• does not accept information about routes that are external to the AS
• uses a default route to reach networks outside of the AS (ABR announces a type 3 LSA containing the default route
• cannot contain ASBRs (except that ABRs may also be ASBRs)

Question 2

What are the characteristics of a totally stubby area in OSPF?

Answer 2

• does not accept external AS routes
• does not accept summary routes from other areas that are internal to the AS
• uses a default route to reach any networks that are external to the area or AS (ABR announces one Type 3 LSA containing the default route, but no other Type 3 LSAs)
• cannot contain ASBRs (except that ABRs may also be ASBRs)
• Cisco proprietary

Question 3

What are the characteristics of an NSSA area in OSPF?

Answer 3

• an addendum to the OSPF RFC
• defines a special type 7 LSA
• similar to a stub area, but allows ASBRs (they inject type 7 external routes into the area)

Question 4

What are the characteristics of a totally NSSA area in OSPF?

Answer 4

• does not accept external AS routes
• does not accept summary routes from other areas that are internal to the AS
• uses a default route to reach any networks that are external to the area or AS
• can contain an ASBR (they inject type 7 external routes into the area)
• Cisco proprietary

Question 5

How to configure a stubby area in IOS-XR?

Answer 5

conf t
router ospf 1
area 2
stub

Question 6

How to configure a stubby area in IOS/IOS-XE?

Answer 6

conf t
router ospf 1
area 2 stub

Question 7

How to configure a totally stubby area in IOS-XR?

Answer 7

conf t
router ospf 1
area 2
stub no-summary

Question 8

How to configure a totally stubby area in IOS/IOS-XE?

Answer 8

conf t
router ospf 1
area 2 stub no-summary

Question 9

How to configure a NSSA in IOS-XR?

Answer 9

conf t
router ospf 1
area 2
nssa

Question 10

How to configure a NSSA in IOS/IOS-XE?

Answer 10

conf t
router ospf 1
area 2 nssa

Question 11

How to configure a totally NSSA in IOS-XR?

Answer 11

conf t
router ospf 1
area 2
nssa no-summary

Question 12

How to configure a totally NSSA in IOS/IOS-XE?

Answer 12

conf t
router ospf 1
area 2 nssa no-summary

Question 13

Which of the LSAs is forwarded into a stub area by an ABR?

A) LSA type 1
B) LSA type 2
C) LSA type 3
D) LSA type 4
E) LSA type 5

Answer 13

C