I'm looking to offer our online services over https and I'm having a couple of problems understanding how to accomplish this. To access our services you must pass through our ISA firewall to a Win2000 server running IIS6. About half our services are located here and the other half take you to a Win2003 server also running IIS6. So, in order to achieve this must each server have the proper certificate installed? ISA, IIS6_1 and IIS6_2? Is there a separate configuration that must be made to our ISA firewall?

The other problem is with the CA and knowing how many certificates I need. It's important to note that the domain name for our services on IIS6_1 is www.domainname.com but the domain name on IIS6_2 is services.domainname.com. I believe that this will require me to purchase more than one certificate. It looks as though we will be going with Thawte's SSL123 as it's a good name and it's fast to get. Will I need to purchase 2 certificates (one for www that will be installed on our ISA firewall as well as IIS6_1, and one for services.domainname.com on IIS6_2)? Or will I need to purchase 3, the extra one being used on our firewall server?

Another side question is about SAN's (subject alternative names). Is this basically adding sub-domains to your cert? So I could purchase one cert with 1 SAN for my www and services.?

Thanks a lot for your help! Please let me know if I can provide any further information.