Can I Use One SSL Certificate on Multiple Domains?

What you need to know about how to use one SSL certificate for multiple domains

We get asked the following question a lot in this industry: “Can I use one SSL certificate on multiple domains?” We have the following response: Yes. Si. Hai. Oui. Da. Ja. Po. Ken. Shì. Tak. Sim. Chai. Evet.

Have we made our point?

No matter what language you speak, no matter what industry you work in, the answer is still the same: Yes, you can use one SSL certificate for multiple domains on the same server. And, depending on the vendor, you also can use one SSL certificate on multiple servers.

How is this possible? It’s a magical website security tool known as a multi domain SSL certificate.

What is a Multi Domain SSL Certificate?

As the name would imply, a multi domain SSL certificate (sometimes written multi-domain SSL certificate) is one that works with multiple domains — the number is left up to the issuing certificate authority. The primary focus is to secure several fully qualified domain names, or what are referred to as DQDNs, which can be a top-level domain or a subdomain. The domain coverage limit is up to 250 domains for many Comodo CA (powered by Sectigo) multi-domain certificates — but more on that a little later.

This differs from a single domain SSL certificate mainly in the number of items that can be covered. As you’ve now probably guessed, a single domain SSL certificate is one that secures a single domain (both the WWW and non-WWW variations).

There are a few other names you may have heard for SSL certificates that fall within the “multi domain” category that we’ll briefly touch on so they don’t feel left out:

SANs

That’s right, you may have heard of SAN certificates. Although this may make things a bit more complicated, just try to stick with us here: A multi domain SSL certificate is sometimes referred to as a SAN certificate. That’s because every multi domain certificate has additional fields (SANs) that you can use to list additional domains that you want to cover under one certificate.

UCCs

Confused yet? Just to make it a bit more tricky — multi domain certificates are also sometimes called unified communications certificates (UCCs) because those are types of multi domain certificates that designed specifically for use on Microsoft Exchange and Office Communications servers.

Multi Domain Wildcards

Oh, and we haven’t even talked about multi domain wildcard SSL certificates yet… Those are SSL certificates that cover multiple domains and an unlimited number of subdomains. However, that’s a topic for another time — let’s just stick with answering the question that led you here about whether you could use one SSL certificate on multiple domains.

Enough of that. Back to the topic at hand. 

What Are the Benefits of Using a Multi Domain SSL Certificate?

As we mentioned earlier, multi domain certificates typically secure up to a total of 250 domains depending on the certificate authority (CA). This number is a bit different, though, for some multi-domain SSL certificates issued by Comodo CA (powered by Sectigo) specifically because select types of Comodo CA multi domain certificates can cover up to 2,000 SAN (subject alternative name) domains. How do you like them apples?

Validation on Multiple Domains

Multi domain SSL certificates are issued with an option of validation levels:

• Domain validation (DV),
• Organization validation (OV), and
• Extended validation (EV).

DV validation — the most basic level of validation — lets end users know that your site has been authenticated by a CA. OV and EV validation, however, take this authentication to higher levels by offering basic (OV) or more extensive (EV) organization validation in addition to validating the domain.

Enhanced Site Security

Have you ever felt the urge to hand over your credit card or personal information to a cybercriminal and wanted to tell them to go have fun with it? Maybe to take a trip to a theme park or take a vacation on your dime? Probably not. The same can be said about your website users. No one wants to do business on an unsecure website. They want to know and feel confident that any information they provide is safe and secure.

This means you need to use the secure HTTPS protocol instead of the non-secure HTTP protocol. HTTPS, or Hypertext Transfer Protocol Secure, is all about creating an encrypted channel

Like other SSL certificates, a multi domain SSL certificate facilitates an encrypted connection that protects data in transit. This means that it protects the plaintext (unencrypted) data that transmits between the client (your site users) and your web server(s) by sending it via a secure, encrypted communication channel.

Other Uses for a Multi Domain SSL Certificate

Not interested in covering multiple domains but want to secure other things? That’s okay — multi domain SSL certificates are very versatile and can help with that. You can use one to secure the following on one or more servers:

• Multiple subdomains, or
• Up to 250 external IP addresses.

Oh, we’re not done yet. There are still additional uses for multi domain SSL certificates that we’ve not yet mentioned. These certificates help you to:

• Save money by purchasing just one certificate (instead of tens or hundreds) to cover multiple domains;
• Avoid costly certificate expiries that can result in outages and downtime, non-compliance fines, and reputational damage; and
• Increase efficiency by only having to track and manage just SSL certificate instead of multiple certificates and their corresponding private keys;
• Save your hair by no longer wanting to pull it out by the handful.

Suffice to say, we think this article answers your question “can I use one SSL certificate on multiple domains?”  But don’t just take our word for it. See for yourself how you can streamline your certificate management tasks, stay compliant, and save money by securing your domains with one SSL certificate.

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