When a router receives an IP packet, it compares the destination address against multiple matching entries in its routing table. In what sequence does the router evaluate these routing criteria to select the single best path for forwarding?
- 1Longest Prefix Match (selecting the route with the most specific subnet mask)
- 2Lowest Administrative Distance (selecting the most believable route source)
- 3Lowest Metric (selecting the optimal path cost within the same routing protocol)
Answer
The correct order of route selection evaluation is: 1. Longest Prefix Match, 2. Lowest Administrative Distance, 3. Lowest Metric.
Routers follow a strict hierarchy to determine the best path. First, the router checks for the longest prefix match to find the most specific network destination. If multiple candidate routes share the exact same prefix length, the router compares administrative distance to select the most reliable routing source. Finally, if routes originate from the same protocol and prefix length, the router uses the metric to break the tie.
Step-by-Step Solution
Key Concept
Route Selection Order of Precedence