Cisco ENCOR Routing Protocols 1 — Questions and Answers
Question 1: What OSPF router type connects one or more areas to the OSPF backbone (Area 0)?
- Internal Router
- Area Border Router (ABR) (Correct answer)
- Autonomous System Boundary Router (ASBR)
- Backbone Router
Correct answer: Area Border Router (ABR)
An ABR (Area Border Router) connects one or more OSPF areas to backbone Area 0 and maintains separate LSDBs for each area it belongs to.
Question 2: What is the administrative distance of OSPF internal routes on a Cisco router?
- 90
- 100
- 110 (Correct answer)
- 120
Correct answer: 110
OSPF internal routes have an administrative distance of 110 in Cisco IOS, making them less preferred than EIGRP (90) but more preferred than RIP (120).
Question 3: Which LSA type is generated by an ASBR to advertise external routes into the OSPF domain?
- Type 1 (Router LSA)
- Type 3 (Summary LSA)
- Type 5 (AS External LSA) (Correct answer)
- Type 7 (NSSA External LSA)
Correct answer: Type 5 (AS External LSA)
Type 5 AS External LSAs are originated by ASBRs and flooded throughout the entire OSPF domain except into stub areas.
Question 4: In EIGRP, which concept refers to the best backup route that is guaranteed loop-free without requiring a query?
- Successor
- Feasible Successor (Correct answer)
- Reported Distance
- Feasible Distance
Correct answer: Feasible Successor
A Feasible Successor satisfies the Feasibility Condition (its Reported Distance < current Feasible Distance), guaranteeing it is loop-free and can be used immediately upon failure of the primary path.
Question 5: What is the default OSPF hello interval on a broadcast (Ethernet) network type?
- 5 seconds
- 10 seconds (Correct answer)
- 20 seconds
- 30 seconds
Correct answer: 10 seconds
On broadcast network types, OSPF uses a default hello interval of 10 seconds and a dead interval of 40 seconds (4x hello).
Question 6: Which EIGRP metric components are used by default in the composite metric calculation?
- Bandwidth and Reliability
- Delay and Load
- Bandwidth and Delay (Correct answer)
- Bandwidth, Delay, Reliability, Load, and MTU
Correct answer: Bandwidth and Delay
By default, EIGRP uses only Bandwidth and Delay (K1=1, K3=1) in its composite metric; Reliability, Load, and MTU have K-values of 0.
Question 7: Which BGP technique artificially lengthens the AS path to make a route less preferred by external peers, influencing inbound traffic?
- Increasing Local Preference
- Lowering MED
- AS Path Prepending (Correct answer)
- Setting Weight to 0
Correct answer: AS Path Prepending
AS Path Prepending repeats your own AS number multiple times in the AS_PATH attribute, causing external peers (who prefer shorter paths) to choose an alternate entry point.
Cisco ENCOR Routing Protocols 1
What OSPF router type connects one or more areas to the OSPF backbone (Area 0)?