This entry was posted on Sunday, February 10th, 2013 at 3:28 pm and is filed under Fun Things, Internet.
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Michael, a traceroute tries to determine the ip address and name of computer your packet passes before it arrives at the final destination.
So you can see what path it takes.
In a bit more depth: if you sent something to another computer, it is not send there straight-away, but you send it to a computer that might now where it can be send. That computer, in its turn, sends it to computer it thinks might now where to deliver it. Etc. Every step is called a hop. On your network your packet would first go to your wifi router, the wifi router sends it to the server from your ISP it is connect to, this will send it to the server that connects your ISP to another ISP etc.
So a traceroute prints the names of all these computers.
Technically it is not immediately obvious how they get the names/descriptions you see, as usually names should be like a.co.nz or b.net.nz etc. That’s the real cool part.
It works by using the time to live counter. Each network node a message passes through deducts one from the TTL. Once the TTL goes to zero the node replies to the sender saying TTL expired at ip address of node. The sender starts by sending with TTL = 1, then 2, 3 etc. That way the sender discovers the path through the network. The traceroute or tracert (windows) program then does a DNS look up on each of the expiring node ip addresses to see if there is an associated DNS name. They have set up the ip addresses in the last few hops with DNS names to spell out the star wars stuff.
The names work because the names coughed up by DNS ptr records don’t have to be genuine DNS names. All you need is authority for the in-addr-arpa zone for the corresponding address block.