Coldfusion: DNS Reverse Lookup « You Give Love a Bad (Dot) Name

I have no idea why this information was so difficult to find, but I'm posting it here in case I ever need it again.

To do a reverse lookup in coldfusion:

<cfscript>
rawIP = createObject("java", "java.net.InetAddress").getByName('#ipaddress#').getAddress();
hostname = createObject("java", "java.net.InetAddress").getByAddress('#rawIP#').getHostName();
chostname = createObject("java", "java.net.InetAddress").getByAddress('#rawIP#').getCanonicalHostName();
</cfscript>

Note — this is slow. If you're doing them in bulk, you may need to go in small batches or set a higher timeout.

Also, this was perhaps useful: http://api.hostip.info/get_html.php?ip=#ipaddress#&position=true — returns the country, city, state, and geotag info for an IP address, where available.

3 Responses to “ Coldfusion: DNS Reverse Lookup ”

Greg says:

June 10, 2009 at 1:46 pm

This works great if it wasnt so slow. We're using this to log the host names of our users, and Im looking up anywhere between 6-10k addresses at a time, which doesnt make this usage feasible. What we've noticed though, is that it only takes a while if it is unable to find a host name. Otherwise, its back in less than a second. Do you or anyone know of any way to cancel the request if it takes longer than a specified period of time and just move on to the next one if that's the case?