A network engineer is configuring a core router that receives routes to the destination network from two distinct dynamic routing sources simultaneously:
- An OSPF advertisement with a calculated path metric of
- An Internal EIGRP (iEIGRP) advertisement with a calculated path metric of
Which path will the router install into its active IPv4 routing table for the network, and what is the primary reason for this selection?
- The Internal EIGRP path, because Internal EIGRP has a lower administrative distance () than OSPF ().Answer
- BThe OSPF path, because OSPF has a significantly lower metric () than Internal EIGRP ().
- CThe OSPF path, because link-state protocols take precedence over distance-vector and hybrid protocols in enterprise routing tables.
- DBoth paths will be installed into the routing table to enable equal-cost multi-path (ECMP) load balancing.
Answer
The router installs the Internal EIGRP path because Internal EIGRP has a lower Administrative Distance (90) than OSPF (110). Metric values are protocol-specific and only evaluated after administrative distance comparison.
When a router receives multiple routes for the exact same network prefix from different routing protocols, it compares their Administrative Distance (AD). Internal EIGRP has a lower default AD (90) than OSPF (110). Because lower AD values are preferred, the router selects and installs the Internal EIGRP route into the routing table. Metric values are never directly compared between different dynamic routing protocols.
Step-by-Step Solution
Key Concept
Administrative Distance vs. Routing Metric in Path Selection