Will my SSL Certificate secure the www. subdomain?

It’s safe to say that www. is the most commonly secured subdomain on the World Wide Web.

Many domain owners have their www. subdomain as an exact copy of the root domain due to the commonness of searching for a site by beginning with ‘www.’.

Naturally, when securing a domain with SSL, one might wonder whether the www. subdomain is going to be secured too.

While this is generally the case, it ultimately depends on the type of SSL Certificate in question.

Let’s discuss which SSL Certificates will secure your www. subdomain and how.

Please note that the following only applies to Sectigo and Trustico SSL Certificates and may differ for those issued by other Certificate Authorities.

Single Site SSL Certificates

Single Site SSL Certificates secure the common name specified on an SSL Certificate, as well as its www. subdomain as a SAN. Likewise, the SAN will be the root domain if the common name contains www.

For instance, if the common name on your Single Site SSL Certificate is example.com, then www.example.com will be included as a SAN on the Certificate and vice versa.

This is the case for Single Site SSL Certificates of all three levels of validation. A Single Site EV SSL Certificate will secure the www. counterpart of the common name just the same as a DV.

Multi Domain SSL Certificates

A Multi Domain Certificate is an SSL certificate which hosts multiple domains and subdomains on the single certificate. It is also called a SAN Certificate.

On Multi Domain SSL Certificates, each individual domain must be specified in order to be secured. Unlike on a Single Site SSL Certificate, a domain’s www. counterpart is not automatically secured.

For instance, if the common name on your Multi Domain SSL Certificate is example.com, you will need to include www.example.com as a SAN in order for it to be secured. This is the case for all domains included on the Certificate for which you would like to secure the www. subdomain.

This is the case for Mutli Domain SSL Certificates of all three levels of validation.

Wildcard SSL Certificates

Wildcard SSL Certificates secure a specified domain and all of its subdomains. As www. is a subdomain, the specified domain’s www. counterpart on a Wildcard SSL Certificate will always be secured.

For instance, if the common name on your Wildcard SSL Certificate is *.example.com, www.example.com will be secured due to being a subdomain on the level indicated by the star (*).

This is the case for all Wildcard SSL Certificates, which come in DV and OV but not EV.