Can I perform a DNS lookup (hostname to IP address) using client-side Javascript?

Question

I would like to use client-side Javascript to perform a DNS lookup (hostname to IP address) as seen from the client\'s computer. Is that possible?

Answer 1

Maybe I missed the point but in reply to NAVY guy here is how the browser can tell you the 'requestor's' IP address (albeit maybe only their service provider).

Place a script tag in the page to be rendered by the client that calls (has src pointing to) another server that is not loaded balanced (I realize that this means you need access to a 2nd server but hosting is cheap these days and you can set this up easily and cheaply).

This is the kind of code that needs to be added to client page:

On the other server "someServerIown" you need to have the ASP, ASPX or PHP page that;

----- contains server code like this:

"<% Response.Write("var clientipaddress = '" & Request.ServerVariables("REMOTE_ADDR") & "';") %>" (without the outside dbl quotes :-))

---- and writes this code back to script tag:

   var clientipaddress = '178.32.21.45';

This effectively creates a Javascript variable that you can access with Javascript on the page no less.

Hopefully, you access this var and write the value to a form control ready for sending back.

When the user posts or gets on the next request your Javascript and/or form sends the value of the variable that the "otherServerIown" has filled in for you, back to the server you would like it on.

This is how I get around the dumb load balancer we have that masks the client IP address and makes it appear as that of the Load balancer .... dumb ... dumb dumb dumb!

I haven't given the exact solution because everyone's situation is a little different. The concept is sound, however. Also, note if you are doing this on an HTTPS page your "otherServerIOwn" must also deliver in that secure form otherwise Client is alerted to mixed content. And if you do have https then make sure ALL your certs are valid otherwise client also gets a warning.

Hope it helps someone! Sorry, it took a year to answer/contribute. :-)