SAN Certificate

SAN CERTIFICATE: How does it work?

What Is a SAN SSL Certificate in SSL/TLS?

In the field of IT, you can call SAN a network of storage areas. But its meanings are different when it comes to SSL/TLS, and we will discuss it in this article. In SSL/TLS, SAN is known as Subject Alternative Name. A SAN certificate will allow you to host particular names that you can cover under one SSL certificate. It can help you secure external and internal domain names by using standard encryption of 128-256-bit. As we know we can cover multiple domains with a multiple domain SSL certificate, but some servers do not allow you to install more than one certificate. In that case, a SAN certificate is the best available option both practically and financially.

A SAN certificate is also known as a UCC SSL certificate. UCC is the abbreviation of Unified Communication Certificate. It was designed specifically for Microsoft, but you can use it on other servers as well

Differentiating SAN vs Multi-Domain SSL

In a multi-domain SSL certificate, you can manage several FDQN domains. Examples of this are or A multi-domain certificate generally includes SAN fields to secure particular hostnames. It clearly shows that most of the multi-domain certificates have the capability to manage several FDQN domains along with hundreds of SANs.

An important thing to remember: The SAN you add on a certificate is always public. It means that if you don’t want your users to know about the affiliation of your domain with some other domain, you should not add the SAN on the certificate. So, if you are a parent organization that is dealing with dairy products but has some other subsidiary that is dealing in vegetables then you may need to use a different certificate.

How a SAN Certificate Works

Now, we have an understanding of a SAN certificate. The next thing is its working. We will explain it with an example:

Suppose you have a domain “”. If you want to protect several domains, all you need to do is adding these domains to the SAN field of the certificate. The following are some of the examples:


That is enough to understand the working of a SAN certificate.

Where to Find Your Certificate’s SAN Information

If you are browsing a website that is using a multi-domain SSL certificate and decides to act nosey, you can check which other domains are being protected under that certificate. All you need to do is click on the padlock icon present in the address bar and choose the Certificate option. This option will be available right under the Details tab, in the Show dropdown menu, click on the Extensions Only.

To see the details of SANs, click on the third option on the list. It will provide you with a list of all the SANs. That’s all about checking the SANs details. There are many certificate authorities that are offering SANs at different prices. You can review these certificate authorities to choose a suitable option for you.

SAN restrictions

There is not any particular restriction on the hostnames you can secure by using a SAN certificate. But these hostnames should be syntactically valid and proper. However, some certificate authorities can impose some additional restrictions on the number of formats depending on the internal commands or different other decisions.

For example, it’s the usual method to reject random wildcard names as SAN hostnames. It means there is a definite list of names that a SAN certificate can support. Another common practice is encountering a check on the number of names a SAN certificate can support, normally up to 100.

Finally, it is not necessary for a hostname to belong to the same domain name. There is no problem for a SAN certificate to secure a number of names such as:


Benefits of SAN Certificate

A SAN certificate offers a lot of benefits, and we will try to discuss as many as possible in the following paragraph.

The most important benefits of a SAN certificate are as follows:

Greater flexibility:

The most important benefit that a SAN certificate can offer is its flexibility. It is very flexible in approach. Let’s suppose you want to secure two to three main domains with several subdomains for every main domain. You might not be able to secure them by using a multi-domain SSL certificate, but with a SAN certificate, you can secure them all.

Browser compatibility:

When it comes to an SSL certificate, one of the most important things to consider is browser compatibility. If you are thinking of installing a SAN certificate, you will be delighted to know that a SAN SSL certificate is compatible with almost all the major browsers. Not only desktop but also their mobile versions.


When we are talking about SSL certificates, encryption is everything. An SSL is based on encryption. It encrypts all the communication between a user and a server. There are different types of encryption methods being used in the industry. A SAN certificate uses the most advanced encryption method. It offers you standard 256-bit encryption.

Made for ASPs:

The biggest beneficiary of SAN certificates is Application Service Providers (ASPs). An Application Service Provider provides services to different customers on the Internet, and each customer will use a different domain name. They can use a SAN certificate for protecting all of these domain names.

Enhanced Site Security:

If you are in eCommerce, you will want better traffic on your web store. You will like to engage your visitors and make them buy your products. By using a SAN certificate, you can win the confidence of your visitors and turn them into your customers. A SAN certificate can enhance the security of your website.

Where to Use SAN SSL?

The next question that may come to your mind is about the usage of a SAN certificate. The most suitable condition to use a SAN certificate is when you have to secure a server that appears with multiple names. A SAN certificate can offer protection to various primary domains and domains that are listed in it. It is an ideal certificate for larger organizations.

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