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SSL Certificates for Subdomains: Choose the Right SSL Certificate for Your Subdomain

Wildcard SSL certificate is an ideal SSL certificate to secure main domain and its first level subdomains.

SSL certificate is a must online security for any online business. SSL certificates can be of many types including single domain SSL, multi domain SSL, wildcard SSL, etc. SSL certificates can secure main domains, subdomains, and multi-level domains. In this article, we will focus on subdomains and which SSL certificate for subdomains is needed. Let us know about subdomains.

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What are Subdomains?

Subdomains are a part of a primary domain. The structure of subdomains includes the first level subdomain. Main/base domain, and TLD.

what are subdomains

In above examples,

example’ is a primary domain.

‘.com’ is TLD (top-level domain).

image’ is a subdomain of

Why are Subdomains Popular?

Subdomains is for specific categories, campaigns, or groups like blog, image, payment, service, product, etc. Moreover, it is easy to recognize and remember them as all subdomains. Users can easily understand the goal of subdomain’s URL upon seeing like,, which clearly states about their purpose.

Why should I secure all my subdomains with an SSL certificate?

SSL certificate for subdomains is required as there are two reasons to have SSL for subdomains:

Google Supports HTTPS

Since 2014, Google favors HTTPS Everywhere, which is supported by major browsers and operating systems. If you have any subdomain running on HTTP instead of HTTPS then, a browser will show a ‘Not Secure’ warning. As a result, a site visitor will not trust the webpage and have an adverse impression in his mind regarding your website. Moreover, if the subdomain is related to any product or sales then, it can drastically reduce sales and profit in near future. It is better to move all subdomains to HTTPS instead of HTTP.

Data Security

An online website may have different web pages like login page, checkout page, subscription page where users share their login credentials and payment information. If these details travel in plain text between the server and the user’s browser, then, attackers may trace and capture this information and misuse it. In the case of a secured subdomain, all the information will travel in an encrypted format hence, it is impossible to ascertain the passing details.

Is It Possible to Secure my Domain and Subdomain with a single SSL certificate?

If you buy a single domain SSL for each subdomain then, it will be a costly deal and hard to manage each subdomain. In this case, you should find an ideal SSL for subdomains. And the answer is a wildcard SSL certificate.

A wildcard SSL certificate can secure the first level of subdomains under the main domain. When you wish to secure subdomains, you should put an asterisk (*) before the primary domain. An asterisk allows unlimited subdomains under the main domain.


In the above image, we can say that * is the main domain that can secure as well as the first level of subdomains like


To secure multi-level domains and subdomains, multi domain wildcard SSL can be of great help. With it, you can secure multiple main domains and their first level of subdomains. Below is an example that will give an idea of a multi domain wildcard certificate.

Regular wildcard SSL Scenario

* can secure,

Multi Domain wildcard SSL Scenario

If you wish to add different levels of domains and their subdomain then a multi domain wildcard is necessary.

  • * can secure
  • * can secure
  • * can secure

The above examples show multi-level domains and can secure their respective first level of subdomains.

Best SSL Certificates for Subdomains

  Best Buy
Product Name AlphaSSL Wildcard Certificate Comodo PositiveSSL Wildcard Certificate Comodo Multi Domain Wildcard SSL
Algorithm SHA-2 Enabled SHA-2 Enabled SHA-2 Enabled
Search Engine Visibility SSL will boost Google rankings SSL will boost Google rankings SSL will boost Google rankings
Validation Type Domain Validation - DV Domain Validation - DV Domain Validation - DV
Issuance Time 15 minutes or less 15 minutes or less 15 minutes or less
Domains Secured Unlimited subdomains Unlimited subdomains Multiple domains & its unlimited subdomains
Server Licenses Unlimited Unlimited Unlimited
CSR Encryption 2048-bit 2048-bit 2048-bit
SSL Encryption Up to 256-bit Up to 256-bit Up to 256-bit
Mobile & smartphone support 99% 99% 99%
Browser compatibility 99% 99% 99%
Client OS compatibility 99% 99% 99%
Includes Malware Scan
Includes Trust Seal AlphaSSL Site Seal Comodo Positive SSL Site Seal Comodo PositiveSSL Site Seal
Reissuance Unlimited during certificate lifespan Unlimited during certificate lifespan Unlimited during certificate lifespan
Warranty $10,000 USD $10,000 USD $10,000 USD
Refund Policy 30 days full money back 30 days full money back 30 days full money back
Vendor Price
Now Only

FAQs for Subdomain Security

How can I secure my second level subdomains?

You can secure a second level subdomain with regular wildcard SSL and multi domain wildcard SSL certificate. For example, to secure, you need to purchase a wildcard SSL for * and will be the first level subdomain. In multi domain wildcard case, will be shown as a SAN.

Can I secure different TLDs with a wildcard SSL certificate?

Different TLDs refers to different domain names, so you can secure different TLDs (.com,, .edu) with multi domain SSL or multi domain wildcard SSL certificates.

Is wildcard necessary to secure www and non-www version of a domain?

No, a single domain SSL certificate can secure both www and non-www domains. The wildcard is for subdomains’ security.

Is wildcard + EV SSL possible?

No, wildcard and Extended Validation (EV) combination are not possible as wildcard does not verify its subdomains and secures the first level of subdomains automatically. On other hand, EV SSL verifies each domain added to the certificate. For wildcard SSL, there are only domain validation (DV) and organization validation (OV) options available.

How can I find the cheapest wildcard SSL?

You can find AlphaSSL wildcard at $26.00/year. which is highly low-cost wildcard SSL certificate that can secure first level of subdomains.

Can I install a wildcard SSL on multiple servers?

Yes, you can install the same wildcard SSL either regular or multi domain wildcard SSL on multiple servers with a simple free reissue process.

Is multi domain SSL can secure subdomains?

If you are having 1 or 2 subdomains, you can add them to a multi domain SSL certificate. Even, you can go with a wildcard SSL certificate too.

Can WordPress site be secured with a wildcard SSL?

Yes, a wildcard SSL certificate can secure the WordPress site domain and its subdomains too.

How can I install wildcard SSL certificate?

In a brief explanation, you need to sign up, pay the price and start the configuration process for a wildcard SSL certificate. Your SSL provider will guide you through the process.

  • Create a CSR from the desired server.
  • Submit the CSR to the SSL provider.
  • Complete the configuration process.
  • Finish the domain validation process.
  • Get a wildcard SSL certificate from a certificate authority.
  • Once you have a wildcard certificate, install it on the server from which you have created the CSR.


A subdomain is an essential part of any website that lessens the burden of a site holder and offers smooth certificate management as well. The wildcard is a cost-effective deal to secure subdomains. If you are in search for SSL for subdomains and have first level subdomains or want to add subdomains in near future then, a wildcard SSL is a must-buy for your website.

About the Author

Nikita Gupta

Nikita Gupta is a seasoned professional with a master's degree in Computer Applications. She brings over 10 years of profound experience to the realm of technology. Her exceptional expertise spans software security, data security, and mastery in SSL/TLS. When it comes to cutting-edge solutions for securing digital assets, Nikita is a dedicated pro.