What is a Wildcard Certificate and How Does it Work?

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You've probably heard of wildcard certificates, but do you know what they do? In a nutshell, they're digital certificates that allow you to secure multiple subdomains within a single domain. Think of them as a one-stop solution for businesses and sites with multiple subdomains to protect against cyber threats.

Because there are so many different sites with complex needs, a wildcard certificate addresses the significant needs of those sites that serve their content through multiple subdomains.

In this article you will learn: What is a Wildcard SSL certificate? How does it work? And how to get one for your own website. But first, let's start with the basics!

Table of contents

What is a Wildcard Certificate?
How does a Wildcard certificate work?
Differences between Wildcard and Multi-Domain Certificate
How much does a Wildcard certificate cost?
How to get a Wildcard certificate?
What is a Wildcard Certificate?
Wildcard SSL certificates protect a domain and all its subdomains under a single digital certificate. They encrypt data transmitted between a web server and a user's browser, ensuring secure communication over the Internet.

With a wildcard SSL certificate, a domain owner can mobile app development service secure an unlimited number of subdomains without having to purchase separate certificates for each subdomain. This type of certificate is ideal for sites with multiple subdomains or dynamic content where securing each subdomain would be impractical from both a performance and cost perspective.

How does a Wildcard certificate work?


The first step is to create a Certificate Signing Request (CSR) , a formal request to a Certificate Authority (CA) to issue you an SSL certificate . This CSR contains information about your domain(s), including any wildcard domains you want to secure.




For Wildcard certificates only, when generating the CSR you need to add an asterisk () before the domain name you want to secure in the FQDN (Fully Qualified Domain Name) field .

The wildcard character (*) is used to represent any combination of characters in a domain name. When used in a certificate, the wildcard character allows you to protect not only one domain, but all of its subdomains.

Now let's talk about implementation. You can install this single certificate on multiple servers that host different subdomains of your site. This simplifies the management process because you don't have to deal with separate certificates for each subdomain; you have one certificate that protects them all.

The best part is that you can add as many new subdomains as you need, and then reissue your wildcard certificate to secure the new subdomains. However, it is important to understand that wildcard certificates only apply to one domain and its subdomains. If you have multiple domains that need SSL protection, you will need separate wildcard certificates for each domain.

Differences between Wildcard and Multi-Domain Certificate
Unlike wildcard SSL, multi-domain certificates , also known as Unified Communications Certificates (UCC) or Subject Alternative Name (SAN) certificates , secure multiple individual domain names with a single SSL/TLS certificate . While a wildcard certificate secures a domain and all its subdomains within a single installation, a single multi-domain certificate can secure up to 250 domains.