natd or firewall problem?

[Chris Hodgins]

Gelsema, Patrick wrote:
> Thats right, you can do the following:
> Put the ip-address with its FQDn (www.webserverwhatever.com) in every hosts
> file (taken its windows) or in its hosts file on freebsd. Or you run an
> internal DNS with an internal zone for your domain whilst running on the
> internet the external zone.
> 
> Regards,
> 
> Patrick
> 

Out of interest, why would using the external ip address not work. 
Would the packets not just be directed out to the router as per usual 
and then the router would notice it should forward the packets to the 
www server?  What am I missing?  The only problem I can think of might 
be sending packets back to the internal ip address.

Thanks
Chris

[snip]