IP ConnectivityDifficulty 3/5
A router has routes O 10.1.0.0/16 via A (AD 110) and S 10.1.4.0/22 via B (AD 1). Where does it send a packet to 10.1.5.7?
- AIt load-balances between A and B
- BVia A, because OSPF routes are preferred for larger networks
- CVia B, because the /22 is the longest prefix match
- DVia B, because static routes have lower administrative distance
Show answer and rationale
Correct: C. Longest prefix match is evaluated first. 10.1.5.7 is inside 10.1.4.0/22 (10.1.4.0–10.1.7.255) and inside 10.1.0.0/16; the /22 is more specific, so B wins. AD only breaks ties between identical prefixes from different sources.
- B — Route source is not the first criterion.
- D — AD would matter only if both routes were for the same prefix.
- A — Load balancing needs equal prefixes and equal metrics from the same protocol.