[ale] IPs

[Derek Atkins]

Ron Frazier <atllinuxenthinfo at c3energy.com> writes:

[snip]
> Your Internet connection's IP address is uniquely associated with the 
> following "machine name":
>
> c-76-97-157-166.hsd1.ga.comcast.net
>
> So, he not only knows I'm in GA, he knows my ISP.  Not sure how that's done.

"Reverse-DNS."  You can look up data (PTR records) in the
z.y.x.w.in-addr.arpa domain for IP Address w.x.y.z and if the ISP (like
Comcast) has put in information then that's what you'll get.  But it
could be completely random if the IP Address is via your own net-block.

So while Comcast is good about reverse-DNS pointer records, not all ISPs
are, and generally you cannot assume that PTR records contain GEO
information.  For example, I can assure you that 130.207.160.29 is in
Georgia, but DNS certainly wouldn't tell you directly.

-derek

-- 
       Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory
       Member, MIT Student Information Processing Board  (SIPB)
       URL: http://web.mit.edu/warlord/    PP-ASEL-IA     N1NWH
       warlord at MIT.EDU                        PGP key available