What does a traceroute command show?

The traceroute command is a network diagnostic tool used to track the pathway that packets take from one point to another in a network. When executed, it sends packets to the destination and measures the time it takes for each hop (the routers along the path) to respond. The command displays each router's IP address, along with the round-trip time for each hop, effectively illustrating the entire route that the packets traverse through the network. This information is invaluable for troubleshooting network issues, understanding network paths, and optimizing network performance.

In contrast, the other options do not accurately describe the functionality of the traceroute command. A list of active IP addresses pertains more to network scanning techniques rather than path tracing. The actual data contained in packets is not revealed by traceroute; its purpose is not to analyze the contents of packets but to monitor their journey through the network. Lastly, while packet size may be relevant in other contexts, such as when analyzing bandwidth or performance, the traceroute command does not specifically measure or display packet sizes. Thus, the focus of traceroute is on the path and timing of the packet's journey, making the correct answer clear.