Defining Multi-domain SSL

Multi-Domain SSL Certificates — also referred to as SAN (Subject Alternative Names) certificates, or UCC (Unified Communications) certificates — secure multiple domains with a single certificate. This type of SSL is mostly used in Microsoft Exchange/Office server environments.

When you sign up for a multi-domain SSL, the first domain you register will be considered your primary domain. Every domain registered after that will be considered as SANs.

Do I need a SAN certificate?

Multi-domain SAN certificates are ideal if you have a large portfolio of domains with evolving needs. With a multi-domain SSL you can secure completely different domains and subdomains with various TLDs. For example:


You can also add, change, or delete SANs at a later date if needed.

A multi-domain SAN cert is also needed to access certain features in MS Exchange, Office Communications, and Live Communications servers.

When it comes to reissuing and renewing SSLs, as well as general certificate management, a multi-domain certificate makes things a lot more convenient. It will save you time and money in the long run, as you only have to deal with one certificate for all your domains, rather than several separate ones, which can end up being unwieldy, confusing, and costly.

How secure are multi-domain SSLs?

Like all SSLs we offer, multi-domain SSLs come with SHA-256 signature and up to 4096 bit RSA keys, as well as Elliptic Curve Cryptography (ECC) support. In plain english, the strongest level of encryption available for your site.

You’ll need to decide on what level of validation you want from the Certificate Authority (for, this is Sectigo). Validation level doesn’t make any difference to the level of encryption of your SSL, but the extent of background checks that will be carried out on you or your company. Which you go for will be highly dependent on the types of service you want to secure. For instance, a blog or simple personal website probably doesn’t need extensive background checks, while it would be good practice for a vast retail enterprise.

Here is a brief summary of the different validation levels:

  • (DV) Domain Validation – the lowest assurance validation is ideal for blogs and personal websites, with no paperwork needed.
  • (OV) Organization Validation – ideal for sites that have logins and require customer information. OV will verify site owner information.
  • (EV) Extended Validation – The highest level of validation makes EV ideal for e-commerce websites. The CA will make more thorough background checks, and your company information will be available in the browser.

The Multi-Domain SSL (SAN) certificate from secures three domains by default, but can secure up to 100 domains for an added fee. For peace of mind, savings, and high-level encryption for all your domains, buy a Multi-Domain SSL to secure your sites today.

Have more questions about Multi-domain SSLs? Check out our FAQ.

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