200-301 Question 283
Single answerA network engineer is troubleshooting a routing issue in a multi-protocol environment where multiple routing sources are configured. The engineer notices that some routes from EIGRP are not being used, even though they are valid. The network is also running OSPF and RIP. Which factor determines which route is installed into the routing table when multiple routes to the same destination are learned from different protocols?
- A
The metric value of the route
- B
The administrative distance of the routing protocol
- C
The bandwidth of the outgoing interface
- D
The hop count of the route
Show answer and explanation
Correct answer: B
Explanation
Administrative distance is a value used by routers to rank the trustworthiness of routing information from different protocols. When multiple routes to the same destination are learned from different protocols, the route with the lowest administrative distance is chosen for the routing table. In this scenario, even though the EIGRP route is valid, it may not have the lowest administrative distance compared to OSPF or RIP.
- A. Incorrect.
The metric value is used to determine the best path within a specific routing protocol, but it does not determine which protocol's route is installed into the routing table.
- B. Correct.
Administrative distance is the primary factor used to determine which route is chosen when multiple routing protocols provide routes to the same destination. The route with the lowest administrative distance is preferred.
- C. Incorrect.
The bandwidth of the outgoing interface does not directly affect the selection of routes between routing protocols. It may influence the metric calculation for certain protocols but is not a deciding factor in this scenario.
- D. Incorrect.
Hop count is a metric used by some protocols, such as RIP, but it is not the factor used to determine which routing protocol's route is installed when multiple sources exist.