Question

A dual-homed enterprise router learns the prefix 172.20.50.0/24 from three sources simultaneously: an eBGP peer at a partner site, an internal OSPF neighbor, and an EIGRP-learned route redistributed from a branch. All three routes have identical prefix length and are valid. After troubleshooting a traffic path complaint, you notice the router installs the eBGP-learned route in the RIB even though the OSPF path is topologically shorter. Assuming default administrative distances, why does the router prefer the eBGP route?

Accepted Answer

eBGP has an administrative distance of 20, which is lower than OSPF (110) and EIGRP internal (90), so it wins route selection.

Answer

BGP always has the lowest administrative distance of any routing protocol, so both eBGP and iBGP routes are preferred over IGPs.

Answer

OSPF metric is higher than the eBGP MED, and the router compares metrics across protocols to select the best path.

Answer

EIGRP internal routes have an administrative distance of 170, which is worse than eBGP, so eBGP is installed by default.