What is a Wildcard SSL Certificate?

Wildcard SSL Certificates

Wildcard SSL certificates are a big help when you need to secure a large number of subdomains under the same domain. Standard single-domain SSL certificates can only secure one domain or its subdomain — for example, domain.tld or sub.domain.tld.

However, modern infrastructures often include many services, each using its own subdomain. If you only need to secure a few subdomains and already know their names, you should choose a Multi-domain SSL (SAN) certificate. But if you have a large number of subdomains and don't currently know all their names, you should choose a Wildcard SSL certificate.

A Wildcard SSL certificate secures an unlimited number of subdomains, but only at the next level down. If you order for *.domain.tld, this means the SSL will secure domain.tld (the base domain) and all of its first-level subdomains — for example, any.domain.tld, mail.domain.tld, and so on. However, it cannot secure a configuration like *.*.domain.tld. In essence, double-wildcard certificates don't exist; likewise, there's no such thing as an EV Wildcard certificate.

Wildcard SSL certificates can also be used for email and exchange servers, since most modern software can work with them just like UCC (Unified Communication) SSL certificates.

There's also a newer type of Wildcard certificate called Multi-Domain Wildcard certificates, which can secure up to 250 different wildcard domains. This lets you secure an unlimited number of subdomains under 250 domain names. Most of our Wildcard certificates also come with an unlimited server license, letting you install different subdomain variations on different servers and IP addresses.