Many websites are architected by using sub-domains. Each sub-domain focuses on a certain aspect of the business. If many of your sub-domains require security, you should consider Wildcard SSL Certificates. A wildcard SSL certificate secures not just your main domain, but also unlimited sub-domains hosted under your domain name.
A wildcard SSL certificate is virtually the same as any regular SSL certificate in functionality and the security it provides. The validation process of a wildcard certificate is the same as that of a regular SSL certificate. The difference between a regular SSL certificate and a wildcard SSL certificate is that a regular SSL certificate protects your main domain while a wildcard SSL certificate also protects any number of sub-domains you have hosted under your domain.
Here is an example of an ecommerce website and its sub-domains:
YourDomain.com would be your basic domain name, while all the other addresses listed above are sub-domains of YourDomain.com. A regular SSL certificate would secure only YourDomain.com. A wildcard SSL certificate on the other hand would cover the main domain; all the sub-domains listed above and any other sub-domains that may be added to the site.
Why do you need to secure sub-domains?
Technically, a sub-domain is seen as a separate website hosted under the main domain name. Search engines recognize each of the sub-domains as separate sites although the main domain name is the same. If your website is divided into sub-domains as illustrated above, then protecting the main domain is not sufficient. You need an SSL certificate that covers each of the sub-domains on your site. Without securing the sub-domains, customers can be hesitant to do transactions over non-secure sub-domains. It can add security risks that you may want to avoid. Instead of buying separate SSL certificates for each of the domains and sub-domains, you can secure all the sub-domains on your site using just one SSL certificate. This can save you costs as well as the hassle of managing multiple SSL certificates.
Misuse of Wildcard SSL Certificates
Because wildcard SSL certificates secure any number of sub-domains, many providers misuse wildcard SSL certificates and cheat their customers by offering cheap or free “fake” SSL certificates. These providers buy Wildcard SSL certificates for THEIR domain, say “serviceprovider.com”. When their customers need SSL certificates, they create sub-domains under their domain name for the so called secure area of their customers as follows: customer1.serviceprovider.com, customer2.serviceprovider.com, etc. These are meaningless certificates and actually provide no security at all to the customers. They do not even authenticate the identity of the customer and are owned by the service provider and not the customer. This can sometimes create a bad image for wildcard SSL certificates.
Wildcard SSL certificates by themselves are perfectly ethical and actually very useful if your website has many sub-domains that need security. You just need to make sure you buy SSL certificates from legitimate service providers and ensure that you are not cheated under the guise of a free or cheap SSL certificate.