Both the issuing authorities and each category of certificates apply different rules as to the use of a certificate for the www form or non-www form about the domain name for which they are issued.
In Friktoria the two basic categories of SSL certificates are Standard and Wildcard.
Standard provide protection for a domain name, while
Wildcard provide protection for subdomains of a top-level domain.
Rules that applied for each category and each issuing authority about the www or non-www form are :
Geotrust
- Standard : if the SSL issued for www.domain.com, coveres domain.com too
- Wildcard : *.domain.com covers domain.com and www.domain.com
Comodo
- Standard : if the SSL issued for www.domain.com, coveres domain.com too
- Wildcard : *.domain.com covers domain.com and www.domain.com
Symantec
- Standard : ssl certificates cover 2 forms as well
- Wildcard : *.domain.com covers the root domain.com
Thawte
- Standard : ssl certificates cover only www.domain.com form or non-www domain.com form
- Wildcard : *.domain.com does not cover the root domain.com
Τrustwave
- Standard : Categories Premium SSL & Premium EV SSL cover by default both www and non-www form, regardless of which of the two will be registered during the installation of the certificate
- Wildcard : cover where appropriate the root form of the domain name