200-301 Question 295
Single answerA network administrator configures a new router in a network. The router receives a packet with a destination IP address that matches multiple routes in its routing table. How does the router determine which route to use for forwarding the packet by default?
- A
The router chooses the route with the longest prefix match.
- B
The router forwards the packet using the route with the lowest administrative distance.
- C
The router uses the first route it encounters in the routing table.
- D
The router sends the packet to all available routes as a broadcast.
Show answer and explanation
Correct answer: A
Explanation
When a router receives a packet, it uses the longest prefix match rule to determine the most specific route for the destination IP address. This rule ensures that the packet is forwarded along the route that has the highest level of specificity in terms of subnet mask or prefix length. The administrative distance and other factors come into play only when selecting routes from different sources to populate the routing table.
- A. Correct.
Correct. By default, a router uses the longest prefix match rule, which identifies the most specific route to the destination IP address.
- B. Incorrect.
Incorrect. Administrative distance is used to compare source reliability between routing protocols, not to choose between multiple routes already in the routing table.
- C. Incorrect.
Incorrect. Routers do not forward packets based on the order of routes in the table. They use specific decision-making rules such as prefix length.
- D. Incorrect.
Incorrect. Routers do not broadcast packets to all available routes. They make a forwarding decision based on their routing table and the packet's destination IP.