Can you have multiple SSL certificates for multiple domain names on a single Elastic Load Balancer (ELB)?

Having multiple SSL certificates for multiple domain names on a single Elastic Load Balancer (ELB) is indeed permitted using Server Name Indication (SNI). SNI is an extension to the SSL/TLS protocol that allows multiple certificates to be presented on the same IP address and port number. This is particularly useful for scenarios where you have several domain names routed through a single ELB, as it allows for secure connections to each domain using its respective SSL certificate.

When setting up your ELB with SNI, you can associate different SSL certificates with different domain names. This means that clients connecting to your ELB can receive the appropriate certificate for the domain they are accessing, ensuring that proper encryption and identity verification take place for each individual domain.

This flexibility makes ELBs a robust solution for hosting multiple websites or applications under different domain names securely. It’s important to ensure that your ELB is of the Application Load Balancer (ALB) type, as this feature is not available for Classic Load Balancers, which only support a single SSL certificate.

Using SNI as a feature of ALBs allows developers and system administrators to maintain best practices for security while efficiently managing resources in their cloud architecture.