Hi,

Thanks for all the feedback. In this particular situation a computer of a lan is attempting to access a web server outside via dsl connection to the internet. The fixed outside IP does not have a dns lookup. I now believe the problem is that the lan administrator requires reverse dns lookup for any IP responding with traffic comming back into the lan. If the reverse dns lookup fails, then the identity of the outside IP is unknown (who ownes it? what is it?) this might suggest that the outside IP is up to something funny so the server (or firewall or whatever) refuses to admit it to the lan. It's probably a good policy. However, in this case the outside IP is known by the lan users, and known to be ok. So, the administrator could make an exception for this one IP address in his server/firewall configuration. At least that's what I think is going on.

>Hi!
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>You're mixing two completely different things. DNS is just a user-friendly server name. Each DNS can be associated with one or more IP addresses. But these IP addresses must be fixed. But not vise versa - when IP address is fixed, it does not means it have DNS. DNS have nothing to the security or fixed IP addresses. Its just a representation of IP address.
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>Fixed IP address means it is fixed for the computer across network connections, computer startups or dial-up connections. Many network systems configured to allow client computers to 'obtain IP address automatically'. This means that IP address might change. In Windows 2000 it might be changed even without computer restarting. More, such IP address in many systems is local to the LAN where it used. So, when you try to access it from outside world, you cannot because tehre are no such IP address for routers or it will lead to completely another server, but not to the main server of the LAN where locally this IP address used.
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>This is made for security reasons for easy security organization for IP transfer without any firewall. Imagine what will be if some unexperiensed user in your LAN tell someone IP address of his computer and than someone will access it, using some services than access network, than all other resources in LAN causing read a lot of information by such way. Protecting client computers from being addressed from outside world is a good parctice.
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>They can use fixed IP address to access computer from ouside world, but than they will require to set up firewall at their gateway server to prevent to access that IP address by everyone.
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>>>Hi!
>>>
>>>I agree with that idea. When they have no Firewalls, the closing of IP addresses from outside is a good security broking preventive thing. They can use Firewall, however. Good Firewall allos to specify the IP address of the machine from which transferring is accepted. Thus, even with fixed IP address, computer is secured enough. But it also allows to connect to that computer from the special predefined IP address. this is exactly as we do now.
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>>What does this have to do with DNS? IP addresses can still be filtered...