Temporary domain redirection to sub-domain

Which redirect method is best for a temp site-wide redirect?

[Dusted]

We've updated our whole website with a new design, but on a different server to our live site. Rather than having the DNS for the site update to the new server, we're going to temporarily (for up to a week) use a subdomain to let people use the new site. This is to ensure everything works as it should (it's a completely different design, even using php instead of coldfusion).

So we need to redirect users from maindomain.com to sub.maindomain.com for a short period.

What is the best way to do this?

By the way all page links remain the same on the sub domain as on the old domain. So on the old site maindomain.com/randompage.html will still work on sub.maindomain.com/randompage.html

[seoRank]

This is a common problem in re-vamping or site shifting. A couple of things to keep in mind -

1. Will you be using a relative URL (through Base Href)? If yes, the indexed pages will still point to the correct URL when you finally switch.

2. Do you intend to 'remove' the subdomain once the switch is effected? I would advise you to check if search engines have indexed your site (subdomain) before you remove. If they have, you may want to let the subdomain live a little longer before phasing it out.

3. If the content on the main domain and the subdomain is identical, your site can get penalized for duplicate content.

4. Maybe, you can have an 'exclude' comment in your robots.txt file of your server to prevent indexing of the content you do not want to be crawled.