Azure WAF Backend Health - Cert issue

Question

When I'm trying to configure the WAF to reach my RDS Gateway, I'm getting the following error "The Common Name (CN) of the backend certificate does not match the host header entered in the health probe configuration. Either change the probe configuration or add a valid certificate on the backend".

The cert I installed on the gateway is a wildcard cert for my external domain, and have updated the external DNS to the Azure public IP. The external domain name differs from the internal name but surely this is a common situation. Also to confirm the wildcard cert installed is definitely the cert I wish to use. Its an externally signed cert for my external domain.

Also to mention I haven't configured any health probe so I presume the health probe mentioned is created by default with the gateway/waf. I have not changed any config on this.

Answer 1

The issue and how to get this fixed is described here:

Troubleshoot backend health issues in Application Gateway

Maybe this is helpful.

Regards

Andreas Baumgarten

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