D3mon - 2:26 pm on Apr 9, 2012 (gmt 0)
OK, I just got done with the changes. It's not 100% perfect, but close.
1. I copied and pasted the main site (PHP) code to the new host.
2. Tested and configured it to work in the new environment (a few code tweaks)
3. Moved the forums on the existing host (Windows/ASP) from mydomain.com/forums/ to forum.mydomain.com and re-configured.
4. Updated the nameservers on the domain to point to the new host.
5. Configured an A-record for 'forum.mydomain.com' to point back to the IP address of the existing host.
6. Finally, I configured the .htaccess on the new host to take any requests for scripts in the old mydomain.com/forums/[...] and redirect them to forum.mydomain.com/[...]
I learned a lot about DNS and I'm sure I annoyed the new host a bit with my Q's, but we got there in the end. :D
Only problem left is that some of the PHP on the main site connects to the MSSQL running the forums to get some data but now can't because the new hosts doesn't allow this.
I'm looking into cURL (maybe) to get this data in another way.