How to Add Subdomains to Your SSL.com Certificate

Protecting subdomains is essential for comprehensive website security. SSL.com offers two solutions: Wildcard SSL for simplicity and UCC/SAN Certificates for flexibility. Below is a streamlined overview comparing the uses cases for each certificate. For technical guidance and step-by-step implementation instructions, please visit SSL.com’s Knowledgebase.

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Wildcard SSL Certificates

Automatic Coverage

• Secures example.com and all first-level subdomains (e.g., blog.example.com, shop.example.com) without needing to re-process the certificate when new subdomains are added.

Ideal For

1. Simplifying TLS Management Across Subdomains

• Use case: You operate multiple services under a single domain (e.g., api.example.com, mail.example.com, admin.example.com) and want to manage a single certificate. 

• Benefit: Reduces the complexity and overhead of obtaining and managing multiple certificates. 

 

2. DevOps and Automated Deployments

• Use case: Automatically spin up new subdomains for development, staging, or containerized services (e.g., dev-1234.example.com). 

• Benefit: Eliminates the need to request new certs or reissue existing ones when subdomains are created dynamically. 

 

3. Multi-tenant SaaS Applications

• Use case: A SaaS app creates a subdomain per customer (e.g., customer1.example.com, customer2.example.com). 

• Benefit: Allows fast onboarding without creating a new cert per tenant. 

 

4. Testing Environments

• Use case: Create secure test environments under subdomains like test1.example.com, qa.example.com, etc. 

• Benefit: Speeds up testing by covering all subdomains with a single certificate. 

 

5. Internal Services Behind Load Balancers or Gateways

• Use case: Load balancers or reverse proxies route requests to subdomains like node1.example.com, node2.example.com. 

• Benefit: Use a wildcard cert to simplify secure internal routing without duplicating certs across nodes. 

 

6. Email and Messaging Servers

• Use case: Secure subdomains for services like smtp.example.com, imap.example.com, autodiscover.example.com. 

• Benefit: Avoids needing individual certs for each protocol endpoint. 

 

7. Multi-region or CDN Edge Deployments

• Use case: Deploy region-specific subdomains like us.example.com, eu.example.com, apac.example.com. 

• Benefit: Quickly scale global edge points while using one cert. 

Limitations

• No support for multi-level wildcards (e.g.,?*.*.example.com) 
• Cannot protect unrelated domains (e.g.,?example.net) 
• Cannot be used with Extended Validation— Wildcard SSL certificates are available only as Domain and Organization Validation; EV wildcards are not permitted by industry rules 

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UCC/SAN (Multi-Domain) Certificates

Key Steps to Add Subdomains

1. Re-process Your Certificate

   • Navigate to Orders > change domain(s)/rekey in the SSL.com portal.
     

2. Modify SANs

   • Re-use your CSR if organization details stay the same. For this option, click the check box for use previous csr. 

   • Add new hostnames (e.g., api.example.com) or wildcard SANs (e.g., *.example.com). For this option, click the Create CSR link. 
     

3. Validation

   • Subdomains under previously validated roots (e.g., dev.example.com) inherit approval.

   • New parent domains (e.g., example.net) require fresh validation.
     

Wildcard Support Rules

• DV Only — Multi-domain certificates with wildcard SANs are available only as Domain Validation. OV/EV multi-domain certs cannot include any wildcards; every SAN must be an explicit FQDN.

For detailed screenshots and CSR troubleshooting, visit SSL.com’s Multi-Domain Re-processing Guide.

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Certificate Comparison

Feature	Wildcard SSL	UCC/SAN SSL
Subdomain coverage	Auto-covers all first-level subdomains under one root	Manual SAN listing (explicit FQDNs or *.example.com)
Multi-domain support	–	Up to 500 domains & subdomains
Wildcard availability	DV Only	DV Only (OV/EV disallow wildcards)
Cost model	Fixed price per cert	Base price + per-SAN fee

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When to Choose Which

• Wildcard SSL
  Best for dynamic, fast-moving setups like SaaS platforms, marketing teams managing frequent campaigns, and internal environments that spin up many subdomains on a single root domain.
• UCC/SAN SSL
  Ideal for enterprises securing many distinct domains and subdomains under one certificate—such as international brands with multiple localized sites—and when you need explicit control over each SAN.

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Pro Tip – Continuous Peace of Mind

Use SSL.com’s Health Check Monitoring (HCM) service to receive real-time alerts on certificate expirations, misconfigurations, and installation issues before they affect users.

Need Assistance?

• Quick Help: Live chat in the SSL.com portal (bottom-right corner)
• Deep Dive: Email Support@SSL.com for architecture reviews or complex multi-domain setups
• Windows Users: Try SSL.com Manager for streamlined CSR generation and certificate installs on Windows servers