Wildcard records are DNS records that direct requests for non-existent subdomains to a specified resource or IP address.
For example, if you type
help.example.com into your browser and the domain
example.com doesn’t have a defined DNS record for the subdomain
help.example.com, a wildcard record would direct you to the defined resource or IP address in its WILL DIRECT TO field.
Records created at a hostname covered by a wildcard record will stop wildcard resolution for that hostname. For example, if you have an A wildcard record at
*.example.com, and you add an MX record at the hostname
email.example.com, you can no longer serve a wildcard record at
email.example.com. However, you can still add an explicit A record to the hostname
email.example.com if your use case requires it.
To create a wildcard record, enter a
* into the HOSTNAME field when creating a DNS record.
For custom domains, you can add apex wildcard domains which the App Platform validates and issues certificates for.
In App Platform, you can add a wildcard record to your app’s domain to redirect queries for non-existent subdomains to the domain’s root.
For more information on how to manage your App Platform using wildcards, see How to Manage Domains in App Platform.