What Is a Wildcard SSL Certificate? Your Ultimate Guide for 2025

A wildcard SSL certificate enables you to secure unlimited single-level subdomains — here’s what it is and how it works

The Basics: What Is a Wildcard Certificate?

A basic wildcard SSL certificate is a small data file that allows you to secure all of the subdomains that exist on a single level for a single domain (e.g., itsatest.site). For example, you can secure all of your first-level subdomains (e.g., mail.itsatest.site, dev.itsatest.site, and store.itsatest.site) using a single certificate.

Here’s an example of what users will see when you install a wildcard SSL certificate on your website:

This certificate enables the use of authentication and encryption for those subdomains, much like a traditional SSL/TLS certificate. However, unlike a traditional SSL/TLS certificate, you must specify the subdomain level you wish to secure in the certificate’s Common Name field when generating your certificate signing request (CSR).

How? By harnessing the power of the asterisk (*).

What Is the Role of a Wildcard Asterisk? How Wildcard SSL Certificates Work

Aside from looking like a cute little star, the asterisk is a stand-in character that represents all of the subdomain possibilities you want to secure with your wildcard certificate. For example, adding that little star at the front of your primary domain (e.g., *.itsatest.site) secures all of your first-level subdomains under a single wildcard SSL certificate.

Here’s a quick example of what a URL domain’s structure looks like:

It’s amazing how one tiny little character can make all the difference in terms of being able to secure your site’s subdomains.

Subdomain Levels: Why the Asterisk Placement Matters with Wildcard Certificates

When answering a question about what wildcard SSL/TLS certificates are, the location of the asterisk is critical to the conversation. This special character secures a virtually endless number of options for a specific field. For example:

• First-level subdomains (e.g., *.itsatest.site). This placement indicates that the certificate will secure unlimited first-level subdomains (e.g., products.itsatest.site, dev.itsatest.site, and mail.itsatest.site).
• Second-level subdomains (e.g., *.subdomain1.itsatest.site). This indicates that second-level subdomains are covered by the certificate (not first-level subdomains). Examples include login.store.itsatest.site, products.store.itsatest.site, and help.store.itsatest.site.
• Third-level subdomains (e.g., *.subdomain2.subdomain1.itsatest.site). This indicates that third-level subdomains such as tools.products.store.itsatest.site or deals.products.store.itsatest.site are covered by the certificate, not first- or second-level subdomains.

Why Should I Consider Getting a Wildcard SSL Certificate?

Well, if you’re looking for a solution to secure countless resources across your domain, a wildcard SSL certificate is the solution you need. With just one wildcard SSL certificate, you can secure your main site and an unlimited number of first-level subdomains. Whether it’s your main site, a customer portal, an online store, or an email platform, they’re all covered under this umbrella.

So, why go for a Wildcard SSL certificate? 

• It’s a time-saver: You can avoid the hassle of managing multiple certificates for each subdomain. No more jumping through hoops for each subdomain.
• It’s kind to your budget: Investing in a wildcard certificate is an economical choice because you’re investing in a single asset that covers a lot of ground.
• Securing your subdomains is a trust booster: Users feel more comfortable and confident on a secure website that uses encryption to protect their data.

What If You Want to Secure More Than One Level of Subdomains?

As previously mentioned, a basic wildcard certificate can only secure all of the subdomains on a single level. So, if you need to secure one or more additional subdomain levels, you must take one of the following approaches:

1. Get a separate wildcard SSL certificate for each subdomain level you wish to secure. For example, you can use one certificate for *.itsatest.site, a second certificate for *.mail.itsatest.site, and a third certificate for *.login.mail.itsatest.site)
2. Get a multi-domain SSL/TLS certificate instead. Using this approach, you can save the wildcard subdomains as separate items in the subject alternative name (SAN) field (e.g., *.itsatest.site, *mail.itsatest2.site, *.dev.itsatest.site, and *.login.dev.itsatest3.site) of a single multi-domain wildcard certificate.  

Basic Wildcard Certificate vs Multi-Domain Wildcard Certificate

Basically, a multi-domain wildcard SSL/TLS certificate offers more flexibility in terms of what it can cover than its basic wildcard certificate counterpart. Here’s a quick overview of what you should know:

	Basic Wildcard SSL Certificate	Multi-Domain Wildcard SSL Certificate
Example Common Name	*.itsatest.site	itsatest.site (NOTE: it must be a fully qualified domain name)
Primary Domain Coverage	Both the WWW- and non-WWW versions of your primary domain	Includes 3 domains with the ability to cover hundreds of additional SAN domains
Subdomain Coverage	Unlimited single-level subdomains. For example:  *.itsatest.site	Multiple levels of subdomains that are specified as SANs. For example: *.itsatest.site *mail.itsatest2.site *.login.dev.itsatest3.site
When To Use Each Certificate	When you have many subdomains on a single level of one domain that you want to secure using a single certificate	When you have multiple domains to secure, or want to secure multiple subdomain levels simultaneously using a single certificate
Certificate Prices	Prices start at $69.78	Prices starting at $156.02
Warranty	Up to $1.5 million	Up to $250,000
	Shop Wildcard Certificates	Shop Multi-Domain Wildcards

Wondering what wildcard or multi-domain wildcard SSL/TLS certificates look like in the wild? Wonder no more — we’ve got two real-world examples for you right here:

Basic (Single Domain) Wildcard SSL/TLS Certificate

Want to learn more about how to get a wildcard SSL certificate? Check out our other resource that will walk you step-by-step through the process (with screenshots!)

Multi-Domain Wildcard SSL/TLS Certificate

Check out this related resource to see more wildcard SSL certificate examples.

How Much Does a Wildcard SSL Certificate Cost?

The price varies based on several key decisions:

1. Which certificate brand you purchase.
2. How many subdomains you wish to secure.
3. The number of years you’re seeking coverage for those domains.

Typically, the more years of coverage you purchase, the better the savings. Even with reducing certificate validity rates (which will drop to 47-day validity by March 2029), you’ll be able to re-issue your certificate (at no cost to you when you buy multi-year coverage) once per year.

	PositiveSSL Wildcard (DV)	InstantSSL Premium Wildcard (OV)	PositiveSSL Multi-Domain Wildcard (DV)	Comodo Multi-Domain Wildcard SSL (OV)
Type of Wildcard Certificate	Single domain	Single domain	Multi domain	Multi domain
Level of Domain Validation	Domain validation	Organization validation	Domain validation	Organization validation
Secures How Many Subdomains	Unlimited	Unlimited	Secures up to X domains and unlimited specified subdomains	Secures up to X domains and unlimited specified subdomains
Price	Starts at $69.78/year	Starts at $102.97/year	Starts at $156.02/year	Starts at $265.78/year
	Add To Cart	Add To Cart	Add To Cart	Add To Cart

A versatile SAN-supported wildard certificate, such as the Comodo Wildcard Multi-Domain SSL, enables you to:

• Add up to 1,000 domains
• Secure an unlimited number of subdomains across multiple domains, and
• Including both first-level subdomains like shop.mydomain1.com and second-level subdomains like mycart.shop.mydomain1.com.

This solution is ideal for organizations operating multiple domain names on a single server. It offers a cost-effective and straightforward approach to web security management.

Wildcard SSL Certificate FAQs

We hope that this article has answered your question, “what is a wildcard SSL certificate?”

If you’re inquiring about a wildcard SSL certificate and are considering buying one, it’s likely you have questions about IP sharing, server, and browser compatibilities. Here’s what you should know to prioritize website security and accessibility when making such an important decision.

Can a Wildcard SSL Certificate Share an IP Address for All Subdomains?

Yes, a wildcard SSL certificate allows all of your subdomains to share a single IP address, simplifying your SSL certificate management and reducing costs​​.

Is a Wildcard SSL Certificate Compatible with All Browsers?

Yes, wildcard SSL certificates are designed to be compatible across virtually all major browsers, ensuring a secure, encrypted connection for users no matter how they access your subdomains​​.

Are There Any Potential Incompatibilities with Wildcard SSL Certificates?

Wildcard SSL certificates are compatible with most modern servers, services, and devices. However, some specific server types may not support them. Although these issues are rare, always check with your provider to avoid any hiccups.

Need a Hand with Your Wildcard SSL Renewal? We’re Here to Help

Like any other digital certificate, a wildcard SSL certificate has an assigned shelf life. Certificate validity is a critical issue, and you have to closely monitor it to stay on top of your certificate lifecycle management to keep your site secure.

But before the clock runs out on your wildcard SSL certificate, it’s time to refresh it via renewal. Without a timely update, your site could start turning away visitors with a glaring security warning instead of welcoming them with open arms.

Is it renewal time for your wildcard SSL certificate? Let’s get you set up.

For Existing ComodoSSLStore Customers

If you’re ready to renew, simply log in to your ComodoSSLStore account and click the “Renew” button to issue your replacement wildcard certificate swiftly.

For New Customers

What if you’re new to Comodo SSL? Start by getting a wildcard SSL certificate and generating a Certificate Signing Request (CSR). For further assistance, our Comodo SSL support team is here to guide you through the process for a smooth and automated certificate management experience.

Editor’s Note: This article was originally published on April 11, 2018. It was updated and republished on April 29, 2025 with new content and graphics to provide you with the most up-to-date information on wildcard SSL certificates.