Sample Questions and Answers
1. Which two EIGRP packet types are used to establish and maintain neighbor relationships?
A. Update and Acknowledgment
B. Hello and Update
C. Hello and Acknowledgment
D. Query and Reply
Answer: C. Hello and Acknowledgment
Explanation:
Hello packets are used to establish neighbor relationships, and Acknowledgment packets confirm receipt of reliable packets like Update, Query, and Reply.
2. What is the default administrative distance of internal EIGRP routes?
A. 110
B. 120
C. 90
D. 170
Answer: C. 90
Explanation:
Internal EIGRP routes have a default administrative distance of 90. External EIGRP routes have a distance of 170.
3. In OSPF, what is the purpose of the Designated Router (DR)?
A. Maintains the shortest path tree
B. Broadcasts Hello packets to all neighbors
C. Minimizes the number of adjacencies on a broadcast network
D. Acts as the primary router for inter-area routing
Answer: C. Minimizes the number of adjacencies on a broadcast network
Explanation:
The DR reduces the number of OSPF adjacencies by acting as a central point for LSAs on broadcast and NBMA networks.
4. What is the purpose of the no auto-summary command in EIGRP?
A. Disables automatic summarization at classful boundaries
B. Enables redistribution between EIGRP processes
C. Forces manual summarization
D. Prevents route flapping
Answer: A. Disables automatic summarization at classful boundaries
Explanation:
By default, EIGRP summarizes routes at classful boundaries. no auto-summary disables this behavior, enabling classless routing.
5. Which BGP attribute is used for loop prevention in an AS-path?
A. Weight
B. Origin
C. Local Preference
D. AS-Path
Answer: D. AS-Path
Explanation:
The AS-Path attribute is used to detect loops in BGP. If a router sees its own AS in the path, it rejects the route.
6. What command is used to advertise a network in BGP?
A. network x.x.x.x
B. advertise network x.x.x.x
C. route x.x.x.x
D. bgp advertise x.x.x.x
Answer: A. network x.x.x.x
Explanation:
The network command under the BGP process is used to advertise networks that exist in the routing table.
7. What is the function of the BGP Local Preference attribute?
A. Determines external route selection
B. Influences outbound traffic from the AS
C. Prevents routing loops
D. Sets the weight of the prefix
Answer: B. Influences outbound traffic from the AS
Explanation:
Local Preference is used within an AS to determine the preferred path for outbound traffic.
8. Which OSPF LSA type is used to advertise inter-area routes from an ABR?
A. Type 1
B. Type 3
C. Type 5
D. Type 7
Answer: B. Type 3
Explanation:
Type 3 LSAs are generated by ABRs to advertise inter-area routes.
9. What is the default hello and dead interval for OSPF on broadcast networks?
A. 10 seconds and 30 seconds
B. 5 seconds and 20 seconds
C. 10 seconds and 40 seconds
D. 30 seconds and 120 seconds
Answer: C. 10 seconds and 40 seconds
Explanation:
On broadcast and point-to-point networks, the default OSPF hello interval is 10 seconds, and the dead interval is 40 seconds.
10. What is the purpose of route redistribution?
A. To eliminate routing loops
B. To configure backup routes
C. To share routes between different routing protocols
D. To summarize routes
Answer: C. To share routes between different routing protocols
Explanation:
Route redistribution enables a router to advertise routes from one routing protocol into another.
11. When configuring redistribution between OSPF and EIGRP, what must be considered to prevent routing loops?
A. Route summarization
B. Route-maps and tagging
C. Administrative distance
D. Stub areas
Answer: B. Route-maps and tagging
Explanation:
Tagging routes during redistribution helps prevent loops by identifying and filtering routes that should not be re-advertised.
12. What is a common reason for a BGP session to remain in the “Idle” state?
A. Prefix is not advertised
B. Neighbor IP is incorrect or unreachable
C. AS path loop detected
D. MTU mismatch
Answer: B. Neighbor IP is incorrect or unreachable
Explanation:
In the Idle state, BGP waits to initiate a TCP session. Incorrect IPs or connectivity issues keep it stuck here.
13. What is VRF-lite primarily used for?
A. Cloud scalability
B. Overlay routing
C. Traffic encryption
D. Network segmentation on a single router
Answer: D. Network segmentation on a single router
Explanation:
VRF-lite allows multiple isolated routing tables on the same router, supporting segmentation for services or customers.
14. In Policy-Based Routing (PBR), which configuration is required to apply a route-map to traffic?
A. Apply route-map under BGP process
B. Use set metric command
C. Apply the route-map to the interface using ip policy
D. Apply a prefix-list to the route-map
Answer: C. Apply the route-map to the interface using ip policy
Explanation:
PBR requires applying the route-map to an interface with the ip policy route-map NAME command.
15. What command verifies redistribution between routing protocols?
A. show ip protocols
B. show ip route
C. show run
D. show ip route redistributed
Answer: A. show ip protocols
Explanation:
This command shows which protocols are being redistributed and their associated configurations.
16. What does the BGP Weight attribute affect?
A. Inbound traffic
B. Route advertisement
C. Outbound traffic preference (locally)
D. AS path loop prevention
Answer: C. Outbound traffic preference (locally)
Explanation:
Weight is a Cisco proprietary attribute used only within a router to influence its outbound route selection.
17. Which feature allows BGP to advertise multiple paths to a destination for load balancing?
A. BGP Multipath
B. Confederation
C. Route Reflector
D. AS Override
Answer: A. BGP Multipath
Explanation:
BGP Multipath allows the router to install and use multiple equal-cost paths for load sharing.
18. Which OSPF area type does not allow type 5 LSAs but allows type 3 and 4?
A. Backbone Area
B. Totally Stubby Area
C. Stub Area
D. NSSA
Answer: C. Stub Area
Explanation:
Stub areas block type 5 LSAs (external routes) but allow type 3 (inter-area) and type 4 LSAs (ASBR info).
19. Which command displays BGP routes received from a specific neighbor?
A. show bgp summary
B. show ip bgp neighbor <ip>
C. show ip bgp
D. show ip bgp received-routes
Answer: B. show ip bgp neighbor <ip>
Explanation:
This command shows the routes received from a specific neighbor and their attributes.
20. What is the purpose of a route reflector in BGP?
A. Reduce eBGP hops
B. Remove the need for IGP
C. Avoid full mesh of iBGP peers
D. Speed up convergence
Answer: C. Avoid full mesh of iBGP peers
Explanation:
Route reflectors allow a scalable iBGP design by reducing the need for full mesh connectivity among routers.
21. Which command is used to summarize OSPF routes on an ABR?
A. ip summary-address ospf
B. area range
C. summary-address
D. network summarize
Answer: B. area range
Explanation:
OSPF route summarization on ABRs is done using the area <area-id> range command.
22. Which metric does OSPF use to determine the best path?
A. Hop count
B. Bandwidth
C. Delay
D. Cost
Answer: D. Cost
Explanation:
OSPF uses cost as a metric, which is calculated based on bandwidth.
23. What is the function of BGP route dampening?
A. Allows faster convergence
B. Penalizes unstable routes
C. Speeds up routing updates
D. Ignores looped routes
Answer: B. Penalizes unstable routes
Explanation:
BGP route dampening minimizes the impact of flapping routes by suppressing frequently changing prefixes.
24. When using EIGRP named mode, where is the metric configured?
A. Under router configuration
B. Under address-family
C. Under topology base
D. Under interface
Answer: C. Under topology base
Explanation:
EIGRP metrics are configured under the topology base section of the address-family configuration.
25. Which protocol uses the Reliable Transport Protocol (RTP)?
A. OSPF
B. EIGRP
C. RIP
D. BGP
Answer: B. EIGRP
Explanation:
EIGRP uses RTP to reliably deliver packets like Updates, Queries, and Replies.
26. What does an EIGRP SIA (Stuck in Active) state indicate?
A. Neighbor down
B. Route not converged
C. Loop detected
D. Packet loss
Answer: B. Route not converged
Explanation:
SIA occurs when a router doesn’t receive a reply to a query and remains in an active state indefinitely.
27. What is the effect of using maximum-paths 4 in EIGRP?
A. Allows up to four neighbors
B. Limits route redistribution
C. Allows load balancing across four equal paths
D. Increases SIA timeout
Answer: C. Allows load balancing across four equal paths
Explanation:
This allows the router to install and use up to 4 equal-cost paths for load balancing.
28. What is the purpose of the redistribute static command?
A. Advertise connected routes
B. Advertise static routes into a routing protocol
C. Summarize static routes
D. Convert static to dynamic
Answer: B. Advertise static routes into a routing protocol
Explanation:
This command injects static routes into the dynamic routing protocol’s database.
29. What does a BGP update message contain?
A. Keepalive and Open parameters
B. Withdrawn routes and new prefixes
C. Only attributes
D. Only AS-path
Answer: B. Withdrawn routes and new prefixes
Explanation:
Update messages carry information about withdrawn routes and new route advertisements.
30. Which command shows OSPF neighbor relationships?
A. show ospf summary
B. show ip ospf neighbors
C. show ospf interface
D. show ip ospf database
Answer: B. show ip ospf neighbors
Explanation:
This command displays the status and details of OSPF adjacencies with neighbor routers.
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