What domain name do I use on my certificate request?
Be careful when choosing your domain name, as you cannot change this information after the certificate is issued. The domain name should be the exact machine server name or hostname you will be using to access your secure pages. For example, if you wish your clients to access https://www.domain.com. You must enter "www.domain.com" as the Domain (or Common) Name in the CSR.
When a browser connects to your SSL site, they will match the domain name accessed, to the one on the certificate. If they do not match, the browser will return an authentication error, so it is important to choose your domain name carefully, prior to making the request. Also, remember that the domain name used, must belong to the company requesting the certificate.