At a loss figuring out if an IP is on LAN or INET

From: "Terry Olsen" <tolsen64@xxxxxxxxxxx>
Date: Thu, 27 Apr 2006 22:03:07 -0600

I'm writing an app that communicates with computers both inside and outside
my router. So I need to determine by the remote host's IP address if I need
to send them my LAN IP or my Internet IP. Someone suggested AND'ing the IP
and my Subnet Mask but I come up with this:

My IP: 192.168.0.14
Mask: 255.255.255.0

Result: 192.168.0.0

Should I just compare the first two octets? Or are there situations where
this would provide incorrect results?

.

Follow-Ups:
- Re: At a loss figuring out if an IP is on LAN or INET
  - From: david
- Re: At a loss figuring out if an IP is on LAN or INET
  - From: Cor Ligthert [MVP]

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