Multiple domains... mirror or redirect?

[Westyfield2]

Just wondering what you guys do and why really. I've always done one, but just asked myself "Why?" and couldn't come up with an answer as to why I do what I do...

So like many organisations you've got more than one domain, but wanting them all to serve up the same content. I'm sure you know the score, over the years you've registered shortname.org, shortname.co.uk, fullname.org, fullname.co.uk, tagline.com, etc. and by now there's links on the internet and printed media floating around with each and every one of them.

Do you:

a) Mirror them. They each work as their own website and the user doesn't know about the others. You enter the website on any and when you drill down you stay on the one you entered. tagline.com/page_name is exactly the same as shortname.co.uk/page_name and the only difference is the URL in the address bar!

b) Redirect them. You pick one domain to be your primary, and then redirect everyone to it. If you went to tagline.com/page_name you are redirected to fullname.co.uk/page_name as fullname.co.uk is your primary domain.​

Yeah, what do you do and why? Are there any advantages or disadvantages of them SEO wise?

 

[Westyfield2]

Redirecting it is then . Consider me learnt!

 

[Westyfield2]

Done it and it all works... but now you've got me scared about whether I've done it correctly as a permanent or as a temporary!


On all the secondary domains:

RewriteEngine On
RewriteBase /
RewriteRule ^(.*)$ http://www.primarydomain.com/$1 [R=301,L]

And on the primary domain:

RewriteEngine On
RewriteCond %{HTTP_HOST} ^primarydomain.com$
RewriteRule ^(/)?(.*) http://www.primarydomain.com/$2 [R=301,L]

That's right... isn't it?