CompTIA Network+ Practice Test

What is a significant limitation when using ICMP messages for traceroute?

1. Some devices may not reply with ICMP Time Exceeded messages

2. Trace routes cannot handle high TTL values

3. ICMP messages cannot provide route details

4. All routers respond to ICMP messages

The correct answer is: Some devices may not reply with ICMP Time Exceeded messages

When using ICMP messages for traceroute, a significant limitation is that some devices may not reply with ICMP Time Exceeded messages. This aspect of ICMP behavior can affect the reliability and accuracy of the traceroute results. When a packet traverses a network, each router along the path decrements the Time to Live (TTL) value until it reaches zero, prompting the router to return an ICMP Time Exceeded message back to the sender. However, if a device or router is configured to disregard ICMP messages or is set to filter them for security reasons, it may simply not respond. This can lead to incomplete results from the traceroute, as some hops in the network path may not be represented if the routers do not send back the expected ICMP messages. In contrast, other choices present scenarios that are not true limitations for traceroute using ICMP. For example, traceroute can indeed handle high TTL values to track routes to distant hosts. Additionally, ICMP messages can provide limited route details, as they reveal the intermediate hops based on the ICMP responses received. Finally, while not all routers respond to ICMP, it is not accurate to say that all routers do this, as some may restrict ICMP traffic. This dynamic