Well, there is a way, it's not definitely right, but usually works. First go to a site like [url]http://www.arin.net/whois[/url] and look up an IP address of a company's site. I did a random IP and got this:
Code:
Comcast IP Services, L.L.C. CABLE-* (NET-7*-0-0-0-*)
7*.0.0.0 - 7*.255.255.255
Comcast IP Services, L.L.C. PITTSBURG-CDM-* (NET-7*-*44-0-0-*)
7*.*44.0.0 - 7*.*47.255.255
# ARIN WHOIS database, last updated 2007-06-*7 **:*0
# Enter ? for additional hints on searching ARIN's WHOIS database.
From what you can see, this Comcast company uses the IP ranges 7*.0.0.0-7*.255.255.255, and their division in Pittsburg uses the IP ranges 7*.*44.0.0-7*.*47.255.255. Somewhere in those IP ranges usually lies the IP for the company's intranet (internal network), and you can't always access it via port 80 (default HTTP port for accessing IPs and domains).