Hot answers tagged subdomain
This is not possible without a wildcard certificate or a certificate for the subdomain. You could create a cert for each of your subdomains using Let's Encrypt though (assuming cost is the issue).
No, in general you need DNS entries (at least one wildcard entry as per your comment) so that the clients know where to look when they call the domain name. Only for strictly local dev purposes, you might get away with defining entries in your hosts file on the client. This would need to be done on every client and usually don't work on mobile devices ...
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