On 6 Oct 2006 at 15:33, Becky wrote:

> I am on a discussion list. I recently came across a web site that
> tells be the geographic location of any IP number. I don't understand
> IP numbers at all. Anyway all but one of the numbers I put in there
> from messages on this discussion list give me a location that I already
> know the posters are from. However one of the posters has over 7or 8
> different IP addresses and none of them even come close to where she
> has stated she is living (Pacific coast). They are all from different
> areas in the Indiana/Illinois area. What do the numbers mean and should
> I assume that the poster has programs or software that is purposely
> hiding her location maybe for privacy reasons?  I am just curious and
> didn't know who to ask how IP numbers work. Thanks 
> 
> Becky Buehrer

  An IP address is a 32-bit number.  But it's special in that internally 
it's divided into two parts:  The first part tells what network it's on, and 
the remainder tells the specific machine.  Escept for a few special cases 
(which we'll ignore), all addresses with the same "first part" are on the 
same network and can see each other directly.  When you (or DHCP from your 
ISP) specifies the "Subnet Mask", it's telling the machine where the 
division between these two parts is.
  That "first part" can be further subdivided, so for instance the first 
part of it indicates the ISP and the next part which of that ISP's networks. 
And so on.
  So everybody who is on ComCast, for instance, might have the same first 
part of their address; ComCast subscribers in the San Francisco Bay area 
probably have a longer shared prefix which is different from the one shared 
by ComCast subscribers in New York.
  Most shorter prefixes are registered with one of several agencies who 
ensure that the same prefix isn't allocated to multiple ISPs:  ARIN for 
North America, RIPE for Europe, APNIC for Asia, and I think there's a fourth 
agency now for Africa and/or South America.  These agencies have websites 
where you can type in an IP address and find out about the applicable 
prefixes known to that agency (or a result telling you which other agency is 
responsible for that address).

  The system isn't foolproof; typically what you get is the location of the 
ISP's office and not of the machine.  When I use my dial-up, I'm seen as 
coming from the city where I live.  When I'm at work, I'm seen as coming 
from the city where our boardroom is, not where my office actually is.  When 
I get on the Google wireless service, suddenly I have an address that 
appears to be in New York.
  So the anomalies you've seen may just be inaccuracies in the available 
information, and not necessarily deliberate attempts to hide or mislead.

David Gillett

         PCBUILD maintains hundreds of useful files for download
                     visit our download web page at:
                  http://freepctech.com/downloads.shtml