Cisco CCNA Static and Dynamic Routing 4 — Questions and Answers
Question 1: A Cisco router has the following entry: 'O IA 172.16.5.0/24 [110/30] via 10.1.1.1'. What does 'IA' indicate?
- The route was learned via an internal OSPF adjacency on the same router
- The route is an inter-area OSPF route learned from an ABR (Correct answer)
- The route is an OSPF external Type 1 route
- The route was imported from an autonomous system outside OSPF
Correct answer: The route is an inter-area OSPF route learned from an ABR
The 'IA' tag in the routing table identifies OSPF inter-area routes that were generated by an Area Border Router from a different OSPF area.
Question 2: Which feature prevents RIP routing loops by immediately marking a route as unreachable when its interface goes down, before the update timer expires?
- Split horizon
- Triggered updates
- Route poisoning (Correct answer)
- Hold-down timers
Correct answer: Route poisoning
Route poisoning immediately advertises a failed route with a metric of 16 (infinity) to notify neighbors quickly rather than waiting for a timeout.
Question 3: What is the administrative distance of a directly connected network on a Cisco router?
- 0 (Correct answer)
- 1
- 5
- 10
Correct answer: 0
Directly connected routes have an administrative distance of 0, making them the most trusted routes in the routing table.
Question 4: An EIGRP router's topology table shows a destination with a Feasible Distance of 28160 and a Reported Distance of 25600. The router has one successor. What correctly describes this entry?
- The route is in passive state and the FD is the metric to reach the destination via the successor (Correct answer)
- The route is active because the RD exceeds the FD
- This entry is invalid because RD cannot be less than FD
- The router will immediately query neighbors because no feasible successor exists
Correct answer: The route is in passive state and the FD is the metric to reach the destination via the successor
In passive state, the FD represents the best metric to the destination via the successor, and a lower RD than FD is normal and expected.
Question 5: Which command configures OSPF to advertise a default route to all OSPF neighbors, even if no default route exists in the local routing table?
- ip route 0.0.0.0 0.0.0.0 null0
- default-information originate
- default-information originate always (Correct answer)
- redistribute static subnets
Correct answer: default-information originate always
The 'default-information originate always' command forces an OSPF router to advertise a Type 5 external default route regardless of whether one exists locally.
Question 6: A static route is configured with an exit interface instead of a next-hop IP. What is a potential issue with this configuration on an Ethernet interface?
- IOS will reject the configuration entirely
- The router will perform ARP for every destination matching that route, potentially flooding the ARP table (Correct answer)
- The route will only work for directly connected networks
- OSPF will not redistribute the route
Correct answer: The router will perform ARP for every destination matching that route, potentially flooding the ARP table
On multi-access Ethernet interfaces, using an exit interface without a next-hop causes the router to ARP for every destination, which can cause excessive ARP entries.
Question 7: What is the OSPF router ID selection order on a Cisco router when no explicit router ID is configured?
- Lowest IP address on any active interface, then lowest loopback address
- Highest IP address on a loopback interface, then highest IP on any active physical interface (Correct answer)
- Lowest loopback address, then lowest physical interface address
- The router ID is always manually configured; there is no automatic selection
Correct answer: Highest IP address on a loopback interface, then highest IP on any active physical interface
OSPF selects the router ID as the highest IP on a loopback interface; if none exists, it uses the highest IP on any active non-loopback interface.
Cisco CCNA Static and Dynamic Routing 4
A Cisco router has the following entry: 'O IA 172.16.5.0/24 [110/30] via 10.1.1.1'.
What does 'IA' indicate?