When securing websites and applications with HTTPS, choosing the right SSL/TLS certificate type is crucial. This guide explains the main types of certificates available and when to use each one.

Validation Levels

SSL/TLS certificates come with different levels of validation, which determine how thoroughly the Certificate Authority (CA) verifies the certificate requester’s identity.

Domain Validation (DV) Certificates

Domain Validation certificates are the most basic and quickest to obtain. The CA only verifies that you control the domain name.

Validation Process:

• Email verification to an admin address (admin@, webmaster@, etc.)
• DNS record verification
• HTTP file verification

Pros:

• Quick issuance (minutes to hours)
• Low cost or free (Let’s Encrypt)
• Automated renewal possible
• Perfect for blogs, personal sites, and development

Cons:

• No organization identity verification
• Minimal trust indicators in browsers
• Not suitable for e-commerce or sensitive applications

Best for: Personal websites, blogs, development environments, internal tools

Organization Validation (OV) Certificates

Organization Validation certificates include verification of the organization’s identity in addition to domain ownership.

Validation Process:

• All DV verification steps
• Legal business verification
• Organization name and address confirmation
• Phone verification of business

Pros:

• Organization details visible in certificate
• Higher trust level than DV
• Suitable for business websites
• Moderate cost

Cons:

• Takes 1-3 days to issue
• Requires business documentation
• More expensive than DV

Best for: Business websites, corporate portals, SaaS applications, customer-facing services

Extended Validation (EV) Certificates

Extended Validation certificates provide the highest level of assurance, with the most rigorous verification process.

Validation Process:

• All OV verification steps
• Extensive legal and physical business verification
• Operational existence verification
• Exclusive domain control verification
• Manual review by CA staff

Pros:

• Highest trust level
• Organization name in browser address bar (some browsers)
• Comprehensive vetting process
• Best for high-value transactions

Cons:

• Expensive (hundreds of dollars per year)
• Takes 3-7 days to issue
• Requires significant documentation
• Annual renewal required

Best for: E-commerce sites, financial institutions, banking applications, payment gateways

Certificate Coverage Types

Beyond validation levels, certificates differ in how many domains or subdomains they can secure.

Single Domain Certificates

These certificates secure one specific fully qualified domain name (FQDN).

Example:

• Certificate for www.example.com
• Does NOT cover example.com (without www)
• Does NOT cover mail.example.com

Use case: Small websites with a single domain

Wildcard Certificates

Wildcard certificates secure a domain and all its first-level subdomains with a single certificate.

Example:

• Certificate for *.example.com covers:
  • www.example.com
  • mail.example.com
  • api.example.com
  • blog.example.com
• Does NOT cover example.com (base domain)
• Does NOT cover dev.api.example.com (second-level subdomain)

Pros:

• Single certificate for multiple subdomains
• Cost-effective for many subdomains
• Simplified certificate management
• Easy to add new subdomains

Cons:

• If compromised, all subdomains affected
• Cannot mix validation levels
• More expensive than single domain
• Some security policies prohibit wildcards

Best for: Organizations with many subdomains, microservices architectures, SaaS platforms

Subject Alternative Name (SAN) / Multi-Domain Certificates

SAN certificates (also called Multi-Domain or Unified Communications Certificates) can secure multiple different domains with a single certificate.

Example:

• One certificate for:
  • example.com
  • www.example.com
  • example.net
  • example.org
  • shop.example.com

Pros:

• Multiple domains in one certificate
• Mix of domains and subdomains
• Cost-effective for multiple domains
• Simplified management
• Can be combined with wildcards

Cons:

• All domains visible in certificate
• Replacing one domain requires reissuing
• Privacy concerns (all domains exposed)
• More complex to manage

Best for: Multi-brand companies, organizations with multiple domains, Microsoft Exchange/Lync servers

Choosing the Right Certificate

Consider these factors when selecting a certificate:

1. Trust Requirements

   • High-value transactions? → EV
   • Business credibility? → OV
   • Basic encryption? → DV

2. Domain Structure

   • Single domain? → Single domain certificate
   • Many subdomains? → Wildcard
   • Multiple domains? → SAN

3. Budget

   • Free/low budget? → Let’s Encrypt (DV)
   • Moderate budget? → Commercial DV or OV
   • High budget? → EV

4. Automation Needs

   • Automated renewal? → DV (Let’s Encrypt)
   • Manual process OK? → OV or EV

5. Issuance Speed

   • Immediate? → DV
   • Can wait days? → OV or EV

Popular Certificate Authorities

• Let’s Encrypt: Free DV certificates with automated issuance
• DigiCert: Premium DV, OV, and EV certificates
• Sectigo (formerly Comodo): Wide range of affordable options
• GlobalSign: Business-focused certificates
• GoDaddy: Popular for small businesses
• SSL.com: Variety of validation levels

Best Practices

1. Use Let’s Encrypt for development and testing
2. Implement automated renewal (especially for DV certificates)
3. Match certificate type to your security requirements
4. Monitor certificate expiration (tools like CrtMgr help!)
5. Keep private keys secure
6. Use strong encryption (2048-bit RSA minimum, prefer 4096-bit or ECC)
7. Enable HSTS (HTTP Strict Transport Security)
8. Implement Certificate Transparency monitoring

Conclusion

The right SSL/TLS certificate depends on your specific needs. For most modern applications, Let’s Encrypt DV certificates provide excellent security at no cost. Businesses requiring identity verification should consider OV certificates, while high-security environments like e-commerce and banking should invest in EV certificates. Use wildcards and SANs strategically to manage multiple domains efficiently.

Need help managing your certificates? Try CrtMgr for automated certificate monitoring, expiration alerts, and renewal tracking!