Question 250
A Cisco router shows `O E2 10.50.138.0/24 [110/20] via 192.0.2.20`. The operations team is unsure whether this prefix is an ordinary OSPF intra-area route or an external route. What does the code identify?
Explanation
Correct Answer
Cisco IOS prefixes route-table codes with their routing protocol and route class. `O E2` identifies an OSPF external type-2 route redistributed into the OSPF domain, while `[110/20]` expresses administrative distance and displayed metric. The external designation is independent of the next-hop address shown after `via`.
Incorrect Answers
Directly connected networks use the C route code. OSPF-learned destinations have O-based codes, with E2 distinguishing an external route class.
The inter-area code is O IA, representing routing across OSPF areas. The E2 suffix specifically indicates an external type-2 route.
A static route uses the S code and may have configurable administrative distance. The O E2 designation identifies the route source even if its displayed distance is 110.