What do the three columns in traceroute output mean?

Traceroute sends out three packets per TTL increment. Each column corresponds to the time is took to get one packet back (round-trip-time).

This tries to account for situations such as:

• A traceroute packet is routed along a different link than other attempts

  11 130.117.3.201 (130.117.3.201) 109.762 ms 130.117.49.197 (130.117.49.197) 118.191 ms 107.262 ms

• A traceroute packet is dropped

  9 154.54.26.142 (154.54.26.142) 104.153 ms * *

In Windows, the traceroute tool will give you the hop number, three columns showing the network latency between you and the hop (so you can average them if you like), as well as the IP address (or hostname if it has a reverse DNS entry) of the hop. From what I remember the output from *nix systems is nearly the same.

"... we have one line for each system or router in the path between me and the target system. Each line shows the name of the system (as determined from DNS), the system's IP address, and three round trip times in milliseconds. The round trip times (or RTTs) tell us how long it took a packet to get from me to that system and back again, called the latency between the two systems. By default, three packets are sent to each system along the route, so we get three RTTs."

Copied from http://www.exit109.com/~jeremy/news/providers/traceroute.html