Cisco ENCOR Routing Protocols 2 — Questions and Answers
Question 1: In Cisco BGP path selection, which attribute has the highest priority and is evaluated first?
- AS Path length
- Local Preference
- Weight (Correct answer)
- MED
Correct answer: Weight
Weight is evaluated first in Cisco's BGP path selection process; it is Cisco-proprietary, local to the router, not advertised to peers, and higher weight is preferred.
Question 2: What does the BGP `neighbor next-hop-self` command accomplish?
- Sets the BGP router ID to the loopback address
- Advertises the router as a route reflector
- Replaces the next-hop attribute with the local router's IP when advertising to iBGP peers (Correct answer)
- Enables BGP confederation functionality
Correct answer: Replaces the next-hop attribute with the local router's IP when advertising to iBGP peers
`next-hop-self` causes the router to substitute its own IP address as the BGP next-hop when advertising routes to iBGP neighbors, resolving next-hop reachability issues common in iBGP.
Question 3: Which OSPF network type requires a DR/BDR election to reduce LSA flooding?
- Point-to-point
- Point-to-multipoint
- Broadcast (Correct answer)
- Loopback
Correct answer: Broadcast
Broadcast network types (default on Ethernet) require DR/BDR elections; point-to-point and point-to-multipoint network types do not elect a DR/BDR.
Question 4: What does the EIGRP Feasibility Condition require for a neighbor to be a Feasible Successor?
- The neighbor's Reported Distance must be greater than the local Feasible Distance
- The neighbor's Reported Distance must be less than the local Feasible Distance (Correct answer)
- The neighbor's Feasible Distance must equal the local Feasible Distance
- The neighbor must be directly connected to the destination
Correct answer: The neighbor's Reported Distance must be less than the local Feasible Distance
The Feasibility Condition states that a neighbor's Reported Distance (RD) must be strictly less than the local router's Feasible Distance (FD) to guarantee a loop-free backup path.
Question 5: Which BGP state indicates that peers have successfully exchanged OPEN messages and are now actively exchanging routing updates?
- Active
- OpenSent
- OpenConfirm
- Established (Correct answer)
Correct answer: Established
The Established state is the final and operational BGP state where the TCP session is up, OPEN messages are confirmed, and UPDATE messages carrying routing information are exchanged.
Question 6: What is the purpose of an OSPF virtual link?
- To create redundant ABR connections within an area
- To connect a discontiguous area to Area 0 through a transit area (Correct answer)
- To allow OSPF adjacencies over non-IP tunnels
- To merge two separate OSPF autonomous systems
Correct answer: To connect a discontiguous area to Area 0 through a transit area
A virtual link logically extends the backbone (Area 0) to an area that lacks direct physical connectivity to it, running through a transit area.
Question 7: What is the default BGP hold time negotiated between Cisco routers?
- 60 seconds
- 90 seconds
- 180 seconds (Correct answer)
- 240 seconds
Correct answer: 180 seconds
Cisco BGP defaults to a hold time of 180 seconds and a keepalive interval of 60 seconds; if no keepalive is received within 180 seconds, the session is torn down.
Cisco ENCOR Routing Protocols 2
In Cisco BGP path selection, which attribute has the highest priority and is evaluated first?