Implementing Cisco IP Routing (CCNP ROUTE, legacy) — Question 109

What happens when a router receives a packet with a TTL of 0?

Answer options

• A. The router attempts to forward the packet along an alternate path in the route table
• B. The router sends an ICMP Time Exceeded Message to the host that sent the packet
• C. The router sends an ICMP Destination Unreachable Message to the host that sent the packet
• D. The router flags the packet and forwards it to the next hop B

Correct answer:

Explanation

When a router receives a packet with a TTL of 0, it cannot forward the packet any further, so it sends an ICMP Time Exceeded Message to inform the original sender. The other options are incorrect because no alternate routing is attempted, and a Destination Unreachable Message is not applicable in this scenario.