Which of the following statements accurately describes how traceroute uses ICMP and RTT?

Correct option is C

1. Traceroute Overview:
· Traceroute is a diagnostic tool used to determine the route (path) packets take to reach a destination.
· It identifies intermediate routers (hops) along the path and measures the Round Trip Time (RTT) for each hop.
2. Mechanism:
· Traceroute works by sending packets with incrementally increasing Time-to-Live (TTL) values.
· TTL is a field in the IP header that determines the lifespan of a packet. Each router decrements the TTL by 1. If TTL reaches 0, the router discards the packet and sends an ICMP Time Exceeded message back to the sender.
· The RTT is measured based on the time it takes for the ICMP Time Exceeded response to return.
Key Points:
1. ICMP in Traceroute:
· ICMP is the primary protocol used by traceroute to receive feedback from intermediate routers (via ICMP Time Exceeded messages).
2. RTT Calculation:
· RTT is the time taken for a probe packet to reach a hop and the corresponding ICMP response to return.
Knowledge Booster:
1. Traceroute Variants:
· On Unix-like systems, traceroute often uses UDP packets by default.
· On Windows, traceroute (tracert) typically uses ICMP Echo Requests.
2. ICMP Messages:
· Echo Request: Used to test connectivity (e.g., in ping).
· Time Exceeded: Sent when TTL expires.
3. TTL Increment:
· The first packet starts with a TTL of 1, the second with a TTL of 2, and so on, to discover each hop in sequence.