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We are experiencing some issues on our IIS server and are trying to narrow down the problem. Basically a site becomes unresponsive to the web. But if we put the domain name (in the hosts file due to local dns issue) on the web server it self the site works fine. So the hosts file has something like:

The IP being one of the IP's on that machine with IIS website setup to listen on port 80 on that IP.

My question is will the request go through the NIC card if (on the web server) we browse to or will it know that it is on the local box already.

What we are trying to figure out is why the site will work on that box but not remotely, either on the local network or through the load balancer to the web. We do not have direct access to the hardware so need to remove as many possibilities remotely as we can.



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up vote 3 down vote accepted

It won't go through the card no, it'll stay 'in machine' - sounds like you have a problem from the NIC 'downwards' (i.e. the NIC itself or switches, routers etc outside the box).

Try swapping the NIC, cabling, port etc. one at a time.

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Brill thanks. That's what we are coming to think, but need to prove it, client also does the hosting, little delicate situation. – Jon Jan 15 '10 at 14:29

The request will not leave the machine. The TCP stack will look at the hosts file first before trying to resolve the hostname using DNS, so the hosts file would still work for local IP addresses/sites even if you were not connected to the network.

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Can you see if the DNS resolution is proper. Also can you run some tool and see if the http requests are reaching the server.

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