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What do the three columns in traceroute output mean?

The man page isn't helpful: http://www.ss64.com/bash/traceroute.html

This is better, but a little more verbose than I'm looking for.

As an example.

traceroute to library.airnews.net (206.66.12.202), 30 hops max, 40 byte packets
 1  rbrt3 (208.225.64.50)  4.867 ms  4.893 ms  3.449 ms
 2  519.Hssi2-0-0.GW1.EWR1.ALTER.NET (157.130.0.17)  6.918 ms  8.721 ms  16.476 ms
 3  113.ATM3-0.XR2.EWR1.ALTER.NET (146.188.176.38)  6.323 ms  6.123 ms  7.011 ms
 4  192.ATM2-0.TR2.EWR1.ALTER.NET (146.188.176.82)  6.955 ms  15.400 ms  6.684 ms
 5  105.ATM6-0.TR2.DFW4.ALTER.NET (146.188.136.245)  49.105 ms  49.921 ms  47.371 ms
 6  298.ATM7-0.XR2.DFW4.ALTER.NET (146.188.240.77)  48.162 ms  48.052 ms  47.565 ms
 7  194.ATM9-0-0.GW1.DFW1.ALTER.NET (146.188.240.45)  47.886 ms  47.380 ms  50.690 ms
 8  iadfw3-gw.customer.ALTER.NET (137.39.138.74)  69.827 ms  68.112 ms  66.859 ms
 9  library.airnews.net (206.66.12.202)  174.853 ms  163.945 ms  147.501 ms
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3 Answers 3

up vote 12 down vote accepted

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 * *

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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.

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"... 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

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bmb

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