What does an asterisk/star in traceroute mean?
The below is a part of
tracerouteto my hosted server:
9 ae-2-2.ebr2.dallas1.level3.net (220.127.116.11) 19.433 ms 19.599 ms 19.275 ms 10 ae-72-72.csw2.dallas1.level3.net (18.104.22.168) 19.496 ms ae-82-82.csw3.dallas1.level3.net (22.214.171.124) 19.630 ms ae-62-62.csw1.dallas1.level3.net (126.96.36.199) 19.518 ms 11 ae-3-80.edge4.dallas3.level3.net (188.8.131.52) 19.659 ms ae-2-70.edge4.dallas3.level3.net (184.108.40.206) 90.610 ms ae-4-90.edge4.dallas3.level3.net (220.127.116.11) 19.658 ms 12 the-planet.edge4.dallas3.level3.net (18.104.22.168) 19.905 ms 19.519 ms 19.688 ms 13 te9-2.dsr01.dllstx3.networklayer.com (22.214.171.124) 40.037 ms 24.063 ms te2-4.dsr02.dllstx3.networklayer.com (126.96.36.199) 28.605 ms 14 * * * 15 * * * 16 zyzzyva.site5.com (188.8.131.52) 20.414 ms 20.603 ms 20.467 ms
What's the meaning of lines 14 and 15? Information hidden?
If a packet is not acknowledged within the expected timeout, an asterisk is displayed.
However zyzzyva.site5.com did eventually respond which is why you have line 16.
Traceroute sends packets to the destination with the field "time to live" (TTL) equal to the number of hops.
Every router decreases the value of TTL of an incoming packet and if it sees an incoming packet with TTL = 0 then drops it, otherwise it decreases the value and sends it further. At the same time it sends diagnosing information to the source about router's identity.
If router does not respond within a timeout then traceroute prints an asterisk. Lines 14 and 15 show that routers which drop packets with original TTLs 14 and 15 did not respond within timeout.
Just to clarify Tim's answer. Tracert is a series of PINGs. The first ping sets the TTL to 1. When the first router receives the PING, it decrements the TTL by 1 and because the new TTL is 0, returns an "error" with it's IP address. Tracert repeats the PING this time with a TTL of 2. Router 1 decrements the TTL by 1, and forwards to router 2. Router 2 decrements the TTL and because it's now 0, returns it's IP address. This process is repeated until either the final destination is reached or the max allowed TTL is reached. If no answer is heard from a PING, tracert displays the *.
Another reason is that typically 3 packets are sent to each machine, and some machines will only respond to the first packet no matter what.
If the problem is just a timeout issue, you can set the
-wparameter to the number of seconds you want to wait; e.g.,
traceroute -w 10 google.comwill wait 10 seconds instead of the default of 5 seconds.
Note: Some traceroute clients use milliseconds instead of seconds for the