How to Secure Second- & Third-Level Subdomains with Wildcard SSL Certificates

If you have a website and want to protect your main site + multiple levels of subdomains, this is where wildcard SSL certificates come in handy.

If you’re looking to secure multiple levels of subdomains with a wildcard SSL certificate, you’re in the right place! A wildcard SSL certificate for nested subdomains (e.g., second-level subdomains [“sub-subdomains”] and third-level subdomains [“sub-sub-subdomains”]) can secure any single level of subdomain, ensuring that every part of your website remains safe and encrypted.

Feeling a bit confused? That’s understandable, and we’ll provide some clarifications shortly. But for those of you following along, you know how useful multiple levels of subdomains can be for larger private and public sector organizations. Knowing this, let’s explore what wildcard SSL certificates are for second-, third-, or multiple-level subdomains. We’ll then jump into how you can use these certificates to protect your web presence efficiently.

An Overview of Wildcard SSL Certificates for Multiple Level Subdomains

There are two approaches for covering multiple subdomains using wildcard SSL/TLS certificates. One approach is to use multiple certificates (traditional wildcard SSL/TLS certificate), one for each subdomain level. This is something to consider if your subdomains are on a single domain.

Another approach is to use a single certificate that covers all subdomain levels simultaneously using a multi-domain wildcard certificate. The certificate’s added benefit is that it enables you to secure multiple domains using one certificate.

Here’s a quick glimpse at the difference between these two options:

	Option #1: Standard Wildcard SSL Certificate	Option #2: Multi-Domain Wildcard Certificate
First-Level Subdomains	Yes	Yes
Second-Level Subdomains	Separate Certificate Required	Yes
Third-Level Subdomains	Separate Certificate Required	Yes
Multiple Domains	Covers a Single Domain Only	Yes
	Shop Wildcard Certificates	Shop Multi-Domain Wildcards

Let’s explore each of these two options more closely.

Option #1: Use Multiple Traditional Wildcard SSL/TLS Certificates

A wildcard SSL certificate can protect any single level of domain. For instance, a wildcard SSL certificate can secure first-level, second-level, or third-level subdomains. However, it can only secure one level at a time — a single standard wildcard certificate can’t be used to secure more than one subdomain level simultaneously.

Here’s how it works: A traditional wildcard SSL certificate uses an asterisk (*) in the domain name to cover all single-level subdomains. For instance, if you have a wildcard certificate for *.example.com, it will secure first-level subdomains like blog.example.com, shop.example.com, and mail.example.com. This asterisk acts as a placeholder, making it possible to cover all possible subdomains at that level.

Image caption: This wildcard SSL certificate for Comodo, shown by the asterisk (*) before the domain name (e.g., *.comodo.com), secures all subdomains under the main domain.

However, the same certificate won’t cover additional levels of subdomains simultaneously, such as:

• Second-level subdomains (*.blog.example.com): store.blog.example.com, login.blog.example.com, and api.blog.example.com.
• Third-level subdomains (*.admin.blog.example.com): app.admin.blog.example.com or login.admin.blog.example.com.

To secure these other levels of subdomains at the same time, you would need to use either:

• A separate wildcard certificate for each level, or
• a single multi-domain wildcard SSL certificate that can secure multiple levels of subdomains (on one or multiple domains) simultaneously.

Need to Secure Multi-Level Subdomains Across Multiple Sites?

If you need to secure multiple levels of subdomains across several domains simultaneously, you’ll need a more advanced solution. This is where option #2 comes into play.

Option #2: Use a Single Multi-Domain Wildcard SSL/TLS Certificate

This type of certificate allows you to secure many domains and their subdomains simultaneously, no matter the level, using a single certificate. This approach is ideal for businesses with a complex web presence, offering flexibility and ease of management.

It must be noted that multi-domain wildcards, also known as “SAN wildcards,” “SAN Multi-Domain Wildcard SSL Certificates,” or “UCC wildcards” are all different names for the same type of SSL certificate. They can secure multiple domains and their subdomains with a single certificate.

Image caption: This SAN certificate for Sectigo covers multiple domains and has the capacity to cover multiple levels of subdomains. Additional domains and subdomains are listed as SAN entries under the “Field Value” section.

How Multi-Domain and Subdomain Coverage Work Together

Scenario #1: E-commerce business with multiple regions and a multitude of subdomains on different levels:

• Domain: shop.com
• Examples of subdomains you can secure using *.usa.shop.com (second level) and *.sales.eu.shop.com (third level) in the certificate’s SAN field:
  • sales.usa.shop.com for the United States region (second level)
  • products.usa.shop.com for the European region (second level)
  • category1.sales.eu.shop.com for promotional offers in the US (third level)
  • category2.sales.eu.shop.com for sales statistics in Europe (third level)

Scenario #2: Educational institution with multiple campuses with multiple levels of subdomains for each location:

• Domain: university.edu
• Examples of subdomains you can secure using *.campus1.university.edu (second level) and *.courses.campus2.university.edu (third level) in the certificate’s SAN field:
  • admissions.campus1.university.edu for admissions at campus one (second level)
  • registration.campus1.university.edu for admissions at campus two (second level)
  • science.courses.campus2.university.edu for science courses at campus one (third level)
  • arts.courses.campus2.university.edu for art courses at campus two (third level)

Scenario #3: Global technology company with offerings for North American and European Union customers:

• Domain: techcorp.com
• Examples of subdomains you can secure using *.na.techcorp.com (second level) and *.products.na.techcorp.com (third level) in the certificate’s SAN field:
  • support.na.techcorp.com for North American support (second level)
  • events.na.techcorp.com for European support (second level)
  • software.products.eu.techcorp.com for software products in North America (third level)
  • hardware.products.eu.techcorp.com for hardware products in Europe (third level)

In these scenarios, a multi-domain wildcard SSL certificate for multiple-level subdomains would be ideal. It would cover all subdomains across multiple sites and subdomain levels.

Have you ever wondered how large websites keep their many sections secure? Now you know one of their secrets! By understanding and using these certificates correctly, you can keep your website secure at all levels with less hassle and at lower cost.

Why Comodo Multi-Domain Wildcard SSL Certificates Are a Smart Choice

Choosing Comodo Multi-Domain Wildcard SSL Certificates is an excellent decision for several reasons:

• Extensive coverage: Secure up to 250 domains and unlimited subdomains with one SSL certificate.
• Cost-effective: Reduces the need for multiple certificates, saving money and resources.
• Simplified management: One certificate for multiple domains and subdomains eases administrative tasks, thereby freeing up your team to work on other high-priority tasks.
• Strong security: Provides 256-bit encryption strength and supports Elliptic Curve Cryptography (ECC).

When you buy a multi-domain wildcard SSL/TLS certificate from ComodoSSLstore.com, you can enjoy:

• Trust and recognition: As a Platinum Partner of the largest certificate authority (Sectigo), we ensure the highest standards in SSL certificates.
• Excellent support: We offer 24/7 support through email, live chat, and phone, ensuring any issues are resolved quickly.
• 30-day refund policy: If you’re not happy with your purchase, that’s okay. ComodoSSLstore.com offers a refund for orders within 30 days of purchase.

So, whether you’re looking to use one or more wildcard SSL/TLS certificates to secure multiple-level subdomains, we’re here to help. Our products provide flexibility and robust security, making them ideal solutions for businesses needing comprehensive protection across various domains and subdomains.