300-440 Question 8
Single answerA network engineer is troubleshooting a routing issue in a multi-protocol environment. The network consists of OSPF, EIGRP, and RIP. A router is receiving the same prefix (192.168.10.0/24) from all three routing protocols, but the router installs the RIP route into the routing table. What could be the most likely cause of this issue?
- A
The administrative distance of RIP has been manually lowered to 80.
- B
The administrative distance of OSPF has been manually increased to 150.
- C
The EIGRP process is not running on the router.
- D
The router's OSPF and EIGRP routes are being filtered by a route-map.
Show answer and explanation
Correct answer: A
Explanation
Administrative distance determines the trustworthiness of a routing source. By default, RIP (120) has a higher administrative distance than both EIGRP (90) and OSPF (110). If the administrative distance of RIP is manually lowered to 80, it will be preferred over both protocols, and the RIP route will be installed in the routing table. Understanding how administrative distance impacts routing decisions is critical for troubleshooting in multi-protocol environments.
- A. Correct.
If the administrative distance of RIP is manually lowered to 80, it becomes more preferred than the default administrative distances of OSPF (110) and EIGRP (90). This would explain why the RIP route is installed in the routing table.
- B. Incorrect.
If the administrative distance of OSPF is manually increased to 150, it would still not explain why RIP is being selected over EIGRP, since EIGRP has a lower administrative distance (90).
- C. Incorrect.
If the EIGRP process is not running, the router would not receive an EIGRP route for the prefix. However, this does not explain why RIP is selected over OSPF.
- D. Incorrect.
If OSPF and EIGRP routes are being filtered by a route-map, the RIP route could be selected as the only available route, but there is no indication of route filtering in this scenario.