What is a wildcard certificate? - c06237161

A wildcard certificate is a digital certificate that is applied to a domain and all its subdomains. Wildcard notation consists of an asterisk and a period before the domain name. Secure Sockets Layer (SSL) certificates often use wildcards to extend SSL-encryption to subdomains.

Extending a single certificate to subdomains rather than purchasing separate certificates can save money and make administration easier. The disadvantage, however, is that if a certificate has to be revoked on one subdomain, it has to be revoked on all the others as well. If a subdomain like payment.domain.com is compromised, for example, so are the mail and vpn subdomains. Purchasing separate certificates may cost a bit more and require more administration, but it also ensures that each subdomain is individually protected.