A router's IP routing table contains four active paths capable of reaching the IP address :
| Prefix / Subnet | Routing Protocol | Administrative Distance |
|---|---|---|
| OSPF | ||
| EIGRP | ||
| RIPv2 | ||
| Static Route |
When a frame containing a packet destined for arrives at the router, which route will be selected to forward the packet?
- The RIPv2 route (), because the longest prefix match is evaluated before administrative distance.Cevap
- BThe static route (), because static routes have the lowest administrative distance value.
- CThe EIGRP route (), because EIGRP has a lower administrative distance than OSPF and RIP for matching networks.
- DThe OSPF route (), because link-state protocols take priority over distance-vector protocols during packet forwarding.
Cevap
The router selects the RIPv2 route () because the longest prefix match (LPM) rule dictates that the route with the most specific subnet mask matching the destination IP address is always selected first.
When a router receives a packet, it performs a lookup in its forwarding table and prioritizes routes based on Longest Prefix Match (LPM). The route with the narrowest host range (longest network prefix mask length) matching the destination IP address is selected regardless of administrative distance or protocol metric. In this scenario, has 28 matching network bits, which is longer than , , or .
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Longest Prefix Match (LPM) Rule
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