<p>I collect statistics on IP addresses from where users visit my site and I have noticed what there are only two IP addresses presented, 172.16.16.1 and 172.16.16.248. The property I use to determine IP address is</p>

<pre><code>Request.UserHostAddress
</code></pre>

<p>What could be a reason of IP address information losing? All the users are from around the world, so they cann't be behind only two proxies.</p>

I assume you are behind a NAT/Reverse Proxy so I think you have to use:
```
```
Request.ServerVariables("REMOTE_ADDR")
```
```
Most likely 172.16.0.0/12 is your privat LAN where 172.16.16.248 is your own address and 172.16.16.1 the address of your router/proxy.