SSL certificate chains are essential for establishing trust in secure connections. Here's a breakdown of key concepts:

What is an SSL Certificate Chain?

A chain is a sequence of certificates that connects a website's domain certificate to a trusted root certificate.

SSL_certificate_chain_structure

Key Components

  • Domain Certificate: Directly issued to your domain (e.g., example.com)
  • Intermediate Certificates: Act as intermediaries between the domain and root certificate
  • Root Certificate: Trusted by default in most browsers and OSes

Verification Process

When a client connects to your server:

  1. The client checks the chain for validity
  2. Verifies signatures between certificates
  3. Ensures the root is trusted
SSL_certificate_verification_process

Configuration Tips

  • Always include the full chain in your server configuration
  • Use openssl to verify chain completeness: 
    openssl verify -chain your_certificate.pem
  • For more details on SSL setup, see our SSL Configuration Guide.

Common Issues

  • Broken Chains: Cause connection errors ❌
  • Missing Intermediates: Result in browser warnings ⚠️
  • Expiration: Requires renewal before validity period ends 📅

For visual examples of certificate chain configurations, explore our SSL Technical Resources.