cheap reverse dns lookup
<p>Currently, I am running asp.net on a 4.0 Framework. I found one section of my code that is truly expensive for me to use.  I currently get the IP Address and the reverse dns for users accessing my site, however, I am trying to keep performance in mind.</p>

<p>Is there a cheaper alternative to this? </p>

<pre><code>return System.Net.Dns.GetHostEntry(HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"]).HostName;
</code></pre>
