What does the output of traceroute mean?

-5

I entered traceroute bbc.co.uk and a lot of information came up, what is the purpose and meaning of this information?

traceroute

Tom Scott

Posted 2017-01-16T12:17:25.690

Reputation: 63

Hi Tom Scott, thanks for posting in the SU community. Please take some time to be familiar with it by taking the quick tour : http://superuser.com/tour You'll then be able to understand what is a good question and what is not.

– Ob1lan – 2017-01-16T12:24:30.287

Also see How do I ask a good question?

– Ƭᴇcʜιᴇ007 – 2017-01-16T14:05:29.553

Answers

Traceroute shows each hop that a packet has to go through from your host to the destination host (in this case bbc.co.uk).

Each one of these steps is represented in a line. The first column is the hop number. The next three columns show the amount of time to get to that hop. (traceroute sends 3 packets and measures the answer from each one of them).

Finally the IP address and if it's possible the DNS name of the hop.

Using traceroute you can debug a failing connection, discover how far away is a server from you or verify if a site is down or if it's your connection.

If the device or server in the hop is unable to answer the traceroute packets then you'll see stars in the row as a way to show you a timeout in the response.

jcbermu

Posted 2017-01-16T12:17:25.690

Reputation: 15 868

Also, there are 30 lines and only the first line has information in it. In the other 29 lines there are simply 3 stars, what does this mean? – Tom Scott – 2017-01-16T12:30:11.350

@TomScott Probably a firewall is blocking your ICMP packets – jcbermu – 2017-01-16T12:39:38.250

@TomScott These lines are hops that the packet goes through, but for some reason (like a firewall) you can't ping it to find out what it is. – cascer1 – 2017-01-16T13:06:58.447

From traceroute manual:

traceroute - print the route packets trace to network host

traceroute tracks the route packets taken from an IP network on their way to a given host. It utilizes the IP protocol's time to live (TTL) field and attempts to elicit an ICMP TIME_EXCEEDED response from each gateway along the path to the host.

Zumo de Vidrio

Posted 2017-01-16T12:17:25.690

Reputation: 310

Thank you, I was wondering, why do I always get so many dislikes, what is wrong with the question? – Tom Scott – 2017-01-16T12:22:21.127

2You have asked without reading the traceroute manual before. That should be your first step before asking. The second step should be ask to Google :) – Zumo de Vidrio – 2017-01-16T12:23:16.770

Ok. I'll consider this in future, thank you. – Tom Scott – 2017-01-16T12:25:46.253