Multi-Domain SSL Certificate: Everything You Need To Know!

SSL Certificate is a security protocol that protects and secured data in transit between the web server and the user to enhance customer trust and boost SEO ranking. SSL certificates are important for all kinds of organizations managing any type of websites like- blog website or a complex e-commerce website.

Multi Domain SSL Certificate

But what if you have multiple websites with multiple domains for your business? Would you require multiple SSL certificates for each of your multiple domains or sub-domains? What if all the multiple domains are lying on the same web server and deploying multiple certificates on the same web server might not be technically feasible? Would you need to invest additional capital and manpower to manage these multiple SSL Certificates?

Not necessarily. Multi-domain SSL Certificate is an efficient and cost-effective approach to manage online security throughout multiple domains and multiple sub-domains. Let’s understand how multi-domain SSL certificates work and manage the data security of your business website.


Multi-Domain SSL Certificate: Meaning

Multi-domain SSL Certificate is a kind of SSL certificate that secures multiple domains and sub-domains with a single certificate. Another name of multi-domain SSL is SAN (Subject Alternative Name) certificates. The number of multiple domains you can secure with a multi-domain SSL certificate depends upon the CA (Certificate Authority) and the plan you choose.


When To Use A Multi-Domain SSL Certificate?

Let’s take an example of an organization that has three different websites for their multiple business lines and have multiple sub-domains.

For Example:
  • com
  • com
  • com

Here, you can use a multi-domain SSL certificate to protect & secure all above multi-domains and sub-domains under a single certificate. This will save a lot of money that would be consumed in buying a separate certificate for each of the websites. Also, it will save your time of authentication, installation and handling multiple domains separately.


How Does SSL Work?

  • When a visitor visits a site, the server and web browser communicate with SSL/TLS process and ensures an encrypted secure connection.
  • The browser sends a request to the legitimate server and the server responds with a TLS/SSL certificate along with the public key to the browser.
  • The browser checks the certificate and verifies that it is from a Trusted Certificate Authority.
  • The browser sends the symmetric keys to the server and the server decrypts the key with its private key and sends the acknowledgment in the encrypted form and starts the communication.
  • Now, the browser and server can start secured communication and ensures privacy, the integrity of messages, and server security.


SSL Certificate

How Does Multi-Domain SSL Work?

For multi-domain SSL certificates, you must list down all your SANs (Subject Alternative Names) with your CN (Common Name) at the time of filling your CSR (Certificate Signing Request). This information will appear in SAN fields under certificate information. The level of encryption and security is the same for both SANs and CN.

When a client visits a website secured with a multi-domain SSL certificate, the client checks for the validity of the certificate. Further, the verification is done. It will verify and match the URL with any of the names mentioned in the list. If it matches, then a secured connection will be established between the client and the server by the browser.

Multi-Domain SSL may also be referred to as SAN SSL or UC SSL


Domain Validation (DV) is a very basic type of validation wherein CA verifies only the domain ownership. It is only suitable for static websites, blog websites and other websites which do not contain sensitive information.

Organization Validation (OV) authenticates the domain and business ownership. This will give you the level of assurance that you are dealing with the same company whose information is listed on the certificate.

Extended Validation (EV) gives the highest level of authentication. It gives the sign of trust such as dynamic site seals, company’s name displayed when clicked on the lock sign and so on. It serves as a trust and credibility for both businesses and the website.

To ensure comprehensive and effective SSL security with your multi-domain SSL certificate, you must choose the OV or EV level of assurance.



A multi-domain SSL certificate is for those businesses that want to save their valuable time, money and efforts and want a single solution for all domains and sub-domains. Whether you are an SME or a large organization, multi-domain SSL from a right and trusted certificate authority assure a high level of security for your multiple websites.

Choose the security of your website wisely. 

About the Author