Secure Multiple Domains with a Single SSL Certificate 

Secure Multiple Domains with a Single SSL Certificate 

SSL certificate is already a must-have for every website. Not only because they help secure data, but they are also a contributing factor in search engine optimization.  

As your business grows, there comes a time where you’ll create multiple domains/subdomains or websites. Once that happens, wouldn’t you want one single SSL certificate that helps secure all websites’ data? It seems intimidating but if you know how it works, you’ll be surprised of how easy it is.  

Don’t get me wrong, you can still get a single SSL certificate for each website. However, you no longer need to always do that. Simply because you can use one SSL certificate that secures multiple websites. Managing it becomes easy. At the same time, it streamlines security measures on multiple websites.  

Today let’s look at the three different kinds of multi-domain SSL certificates. 

1.Multi-domain/SAN certificates 

A SAN (subject alternative name) certificate is another name for a multi-domain SSL certificate. There is a field in a multi-domain certificate that lets you attach additional host names to a single SSL certificate. These host names can be anything from URLs to IP addresses however are generally DNS (space name framework) names. 

What happens is the browser checks the certificate to see if the URL matches any of the SAN names listed in it. When a user attempts to access the website protected by a SAN/multi-domain certificate, it establishes a safe connection to the server. 

This certificate can protect up to 100 different subdomains and domains, making it ideal for businesses with multiple websites – even websites with multiple versions for different geographic locations. When it comes to renewing certificates, keeping a website security up to date, and other similar tasks, having multiple domains under one unified certificate makes managing them a lot easier. 

2.UCC certificate 

 Like SAN/multi-domain SSL certificates, the UCC (Unified Communications Certificate) is used in office environments that use Microsoft Exchange and Office Communications. UCCs can likewise get up to 100 subdomains and spaces on one certificate and use SAN extensions to secure them. This certificate is ideal for companies that run multiple domains and websites using Office Communications and Microsoft Exchange. 

3.Multi-domain Wildcard SSL Certificate 

Multi-domain Wildcard SSL certificates differ from SAN and UCC certificates. Instead of securing multiple domains, it secures multiple subdomains for a single domain. For instance, if you purchase a Wildcard SSL certificate for ‘’, then subdomains like ‘’ and ‘’ will also be protected by SSL. However, ‘’ and its subdomains wouldn’t be protected automatically – you’ll have to purchase another certificate for it.  

Wildcard SSL certificates allow you to add subdomains in the future, so you don’t need to set these up at the time of purchase – they can be added later. For securing unlimited subdomains and multiple domains, Wildcard SSL can be used in conjunction with UCC and multi-domain certificates. BigRock issues a Wildcard SSL certificate within 2 days and provides a free additional server licence.  

Multi-Domain/SAN/UCC vs. Multi-Domain Wildcard SSL 

Multi-Domain/SAN SSL  Multi-Domain Wildcard Certificate  
A single certificate that secures up to 100 domains and subdomains.  A single certificate can secure unlimited subdomains.  
Limitations on the number of domains covered are usually defined by the issuing certificate authority. 


There are no limitations on the number of subdomains covered.  
The domain names that you wish to secure must be added and defined at the time of purchasing the certificate. However, additional SANs can be acquired later. 


Subdomains can be added or removed at any point in time. 



Example:,, and, etc. can be secured using one certificate  Example: * can secure every subdomain at that level, like,, etc. 


How encryption works for multi-domain certificates 

SSL certificates usually offer the same level of encryption. So, when you choose an SSL certificate for your website, it’s not about how much security it will provide your website. If you get it from a trusted certificate authority, user information would be safe. 

An SSL handshake occurs when a browser visits a website with an SSL certificate. As the user sends the data, it is encrypted and decrypted simultaneously. Until it reaches the source, the data remains “scrambled” rendering it unreadable. 

A secure connection enables the server’s private key and the client’s public key which creates a session key. If a website’s SSL certificate is valid during the process. The session key ensures the safety of the connection. This handshake safeguards the information of users when they are on your website. 

Secure Your SSL Certificate Today 

SSL certificates come with a single domain and multiple domains option. While the idea of securing multiple websites using one SSL certificate seems complex, you can use the setup without hassle through the right providers.

At BigRock, we provide Positive SSL and Comodo SSL certificates for single domains, and Positive Wildcard SSL certificates for multi-domains. Check them today and keep your websites’ security updated. 


Related Article:

Different Types of SSL Certificates Explained

What is SSL Certificate and What are its Benefits

5 Reasons Why SSL Certificate is Important for your website



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