URL Masking with DNS and/or Mod_Rewrite?

Question

I want to setup a system so that multiple custom domains like [mydomain.com/params] will redirect to [myapp.com/mydomain.com/params]. Can I do this using only DNS s

Answer 1

Here's the solution:

1. Set DNS Address records for all vanity domains to the same IP address (so d1.com, d2.com, d3.com, etc. all have DNS A records set to one IP or FQDN for example)
2. Setup the server with one VirtualHost using the IP as the domain
3. Within that VirtualHost's root directory, create a .htaccess that sets up the mod_rewrite
4. Use the following for the mod_rewrite in the .htaccess:

Options +FollowSymLinks

RewriteEngine On

RewriteCond %{HTTP_HOST} (.*) [NC]
RewriteRule (.*) http://myapp.com/%1/$1 [P,R=301,L]

%1 = the domain that is requested, so www.d1.com or d1.com
$1 = the rest of the URL that comes after the vanity URL (d1.com/everyting/else

This config invisibly redirects all requests.

Examples:

d1.com => returns content from => myapp.com/d1.com/

www.d1.com => returns content from => myapp.com/www.d1.com/

d1.com/blog/post/1 => returns content from => myapp.com/d1.com/post/1

Answer 2

No, you can't use only DNS for that.

If every domain can run standalone (www.domain.com) this would be a straightforward multi-site setup and does not require mod_rewrite, just a bunch of <virtualHost> directives that point to each site.

If you need exactly the setup you describe (http://www.hostname.com/www.2ndhostname.com/directoryname) you would need one <VirtualHost> with all the domains as aliases, and a mod_rewrite based redirect to point incoming requests to the right directory.