Absolute maximum number of certificates for Application Load Balancer


According to https://docs.aws.amazon.com/elasticloadbalancing/latest/application/load-balancer-limits.html, the default Limit for Certificates per Application Load Balancers is 25. The site also states that it's adjustable, but I couldn't find any response as to what is the absolute maximum number of certificates.

We're currently planning a new application for existing customers, where each customer gets it's own subdomain and which should be delivered over TLS. So my question is: is there an actual limit as to how many certificates can be added to a single ALB? Just for completeness: there will be only one rule and one target group to handle all customer requests.

1 Answer

While I am not sure about the hard limit, you can use wildcard certificates or certificate with Subject Alternate Names (SANs) with ALB. This way, the number of certificates that you require for your application will be reduced. If you're using AWS Certificate Manager to create / manage your SSL/TLS certificates, you could have up to 100 domain names per certificate. More details on how to add certificates for multiple domains to a load balancer using Certificate Manager can be found in this article .

Finally a working Server Name Indicator (SNI) on ALB demo is available here

answered a year ago

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