1. Refer to the exhibit. What does the “OE2” from the “OE2 0.0.0.0/0 [110/1] via 192.168.1.1, 00:05:34, Serial0/0/1” line represent?
- an internal OSPF route with a metric of 2
- an external OSPF route that is two hops away
- an external OSPF route learned from two different sources
- a redistributed route that will not increment in cost
Explanation: External OSPF routes learned through redistribution are classified as either type 1 or type 2. The O*E2 indicates that this is a type 2 external OSPF route. Type 2 routes carry the same metric through the OSPF domain as it had when learned through the ASBR.
2. What routes are redistributed by default from BGP into IGP protocols when BGP redistribution is configured?
- routes learned through EBGP
- routes learned through IBGP
- routes learned from other IGP protocols
- routes learned from BGP routers in the same AS
Explanation: By default BGP will only redistribute routes learned through EBGP into IGP protocols. To change this behavior the bgp redistribute-internal command can be issued under the BGP routing process so that all BGP routes are redistributed.
3. Refer to the exhibit. What metric will EIGRP routes have as they are redistributed into OSPF Area 0?
- 1
- 2
- 20
- infinity
Explanation: The redistribution configuration exists under the destination protocol and identifies the source protocol. The source protocol, EIGRP in this case, provides the network prefixes that are to be redistributed. Routes redistributed into OSPF from another IGP receive a default seed metric of 20 and a default route type of type 2.
4. Refer to the exhibit. A network administrator has configured two-way redistribution on router R1. What metric will OSPF routes have when they are redistributed into EIGRP?
- 1
- 20
- 170
- infinity
Explanation: The redistribution configuration exists under the destination protocol and identifies the source protocol. Routes redistributed into EIGRP will have a default seed metric of infinity unless a metric is defined.
5. What is the administrative distance of EIGRP-learned routes that have been injected into EIGRP via redistribution?
- 1
- 90
- 100
- 110
- 170
- 180
Explanation: Routes redistributed into EIGRP are external EIGRP routes with an administrative distance of 170.
6. Which statement is true about redistribution behavior?
- Redistributed routes must exist in the RIB.
- Redistribution is transitive.
- Redistribution is not sequential.
- BGP cannot be redistributed into an IGP.
Explanation: For a route to be redistributed it must exist in the RIB. Redistribution is sequential but not transitive. Although BGP can be redistributed into an IGP, it is not always recommended.
7. Which characteristic describes an OSPF type 1 external route?
- It is preferred over type 2 external routes.
- It has a metric that does not change throughout the OSPF domain.
- It has a default seed metric of 1 for all routes except routes redistributed from BGP.
- It is the default external route type used by OSPF.
Explanation: There are two types of OSPF external routes, type 1 and type 2. Type 2 is the default setting if not otherwise specified in the redistribute command. The metric for type 1 routes equals the redistribution metric plus the total path metric. For type 2 routes the metric stays the same as the redistribution metric throughout the OSPF domain. The seed metric for BGP-sourced routes redistributed into OSPF is 1.
8. What is the administrative distance for routes redistributed into OSPF?
- 20
- 110
- 170
- infinity
Explanation: The administrative distance for all OSPF routes is 110.
9. Refer to the exhibit. Which three outcomes will result from the redistribution configurations on router R1? (Choose three.)
- OSPF routes are redistributed into the EIGRP routing domain.
- EIGRP routes are redistributed into the OSPF routing domain.
- OSPF routes are redistributed into the BGP routing domain.
- EIGRP routes are redistributed into the BGP routing domain.
- BGP routes are redistributed into the OSPF routing domain.
- BGP routes are redistributed into the EIGRP routing domain.
Explanation: When redistributing between two protocols the redistribution configuration is issued under the destination protocol and identifies the source protocol.
10. Refer to the exhibit. Which three situations will result from the redistribution configurations on router R1? (Choose three.)
- OSPF routes are redistributed into the EIGRP routing domain.
- OSPF routes are redistributed into the BGP routing domain.
- BGP routes are redistributed into the OSPF routing domain.
- EIGRP routes are redistributed into the BGP routing domain.
- EIGRP routes are redistributed into the OSPF routing domain.
- BGP routes are redistributed into EIGRP.
Explanation: In redistribution between two protocols, the redistribution configuration is issued under the destination protocol and identifies the source protocol. In redistributing between two or more routing protocols on a single router, redistribution is not transitive.
11. Which routing protocol has a default seed metric of infinity for routes redistributed from other routing protocols?
- EIGRP
- OSPF
- IBGP
- EBGP
Explanation: Routes redistributed from other IGPs into EIGRP receive a default seed metric of infinity.
12. What is the default OSPF seed metric for routes sourced from protocols other than BGP?
- 1
- 10
- 20
- infinity
Explanation: Routes learned through another routing protocol are treated as external routes by OSPF. These routes are given a seed metric of 1 if they are learned from BGP or 20 if the routes are learned from another IGP.
“Do I Know This Already?” Quiz Answers:
1. R1 learns the 10.11.11.0/24 prefix from EIGRP. EIGRP is redistributed into OSPF on R1, and OSPF is redistributed into BGP on R1. R1 advertises all the BGP network pre-fixes to R3. Does R3 receive the 10.11.11.0/24 prefix?
- Yes
- No
Explanation: Route redistribution is not transitive on a single router.
2. What is the administrative distance for external EIGRP routes?
- 90
- 110
- 170
- 200
Explanation: The AD for external EIGRP routes is 170.
3. What is the default seed metric for OSPF?
- 20
- 100
- 32,768
- infinity
Explanation: The default seed metric for OSPF is 20.
4. R1 learns the 10.11.11.0/24 prefix from EIGRP. EIGRP is redistributed into OSPF on R1. R1 has an OSPF adjacency with R2. R2 redistributes OSPF into BGP. R2 advertises all BGP network prefixes to R3. Does R3 receive the 10.11.11.0/24 prefix?
- Yes
- No
Explanation: Sequential redistribution is allowed.
5. What is the administrative distance for external OSPF routes?
- 150
- 110
- 180
- 200
Explanation: The AD for external OSPF routes is 110, which is the same as the AD for internal OSPF routes.
6. What is the default seed metric for EIGRP?
- 20
- 100
- 32,768
- infinity
Explanation: The default seed metric for EIGRP is infinity.
7. Which additional command is needed to redistribute external OSPF routes into EIGRP?
- ospf-external-prefixes redistributable
- eigrp receive external source networks
- ospf redistribute-internal
- None
Explanation: External OSPF routes redistribute into EIGRP with the basic redistribution command.
8. Which additional command is needed to redistribute external OSPF routes in to BGP?
- ospf-external-prefixes redistributable
- match external
- bgp redistribute-internal
- none
Explanation: External OSPF routes are not redistributed into BGP with the basic redistribution command; the command match external must also be used.