Which command demonstrates a TCP traceroute?

Which command demonstrates a TCP traceroute?

• A. tracert www.google.com
• B. tcptraceroute www.google.com
• C. ping www.google.com
• D. nslookup www.google.com

Answer: (B)

Understanding how traceroute can use different transport protocols is key. A TCP traceroute sends TCP SYN packets to a specific destination port and watches the path by getting responses from intermediate routers and the final host. The tool designed for this purpose is tcptraceroute, which is built to perform a traceroute over TCP rather than the default UDP or ICMP methods. This makes it especially useful when you want to test reachability to a particular TCP service port and see where traffic is blocked or altered by firewalls or ACLs along the route. In contrast, tracert (on Windows) uses ICMP Echo requests (and sometimes UDP-like behavior), ping uses ICMP Echo to measure reachability, and nslookup queries DNS records. None of these perform a TCP-based route traversal, so they don’t demonstrate a TCP traceroute. Therefore, the command that shows a TCP traceroute is the one that explicitly uses the TCP traceroute utility.

Understanding how traceroute can use different transport protocols is key. A TCP traceroute sends TCP SYN packets to a specific destination port and watches the path by getting responses from intermediate routers and the final host. The tool designed for this purpose is tcptraceroute, which is built to perform a traceroute over TCP rather than the default UDP or ICMP methods. This makes it especially useful when you want to test reachability to a particular TCP service port and see where traffic is blocked or altered by firewalls or ACLs along the route.

In contrast, tracert (on Windows) uses ICMP Echo requests (and sometimes UDP-like behavior), ping uses ICMP Echo to measure reachability, and nslookup queries DNS records. None of these perform a TCP-based route traversal, so they don’t demonstrate a TCP traceroute. Therefore, the command that shows a TCP traceroute is the one that explicitly uses the TCP traceroute utility.