Geo location to IP mapping

Roland Perry lists at
Tue May 16 11:01:19 UTC 2006

In article <Pine.SOC.4.61.0605152255040.4154 at>, Bill 
Woodcock <woody at> writes
>    > I just tried that, says I'm 100 miles south of where I really am. That's
>    > quite a long way out in a small country like England.
>1.3ms is longer in small countries like England?

I'm virtually certain it's not being done by propagation delay.

What they've apparently done is look up the RIPE database, and found 
that my ISP has registered an address, with postcode, for the hostmaster 

They've reported the major town associated with the two most significant 
(out of six) characters of that postcode (Hemel Hempstead), although the 
address is actually in a smaller town twenty miles to the west (Stoke 

To complicate the issue, the ISP is formed by the acquisition of several 
smaller ISPs, and it seems unlikely (from my knowledge of the local 
topology) that the physical NOC is at the hostmaster's address.

Finally, the "tail" from the NOC to my house (which appears as one hop) 
is over a connection into British Telecom's ADSL backbone, and then over 
the BT internal network which supports their wholesale ADSL product, as 
far as my local telephone exchange (which I can see out of my office 
window) and a short length of local copper. There's nothing in either 
the RIPE database, or timing of packets, which could say where in the 
country that tail is delivered. The ISP has my billing address, of 
Roland Perry

More information about the NANOG mailing list