Ask a precise question
An A record identifies an IPv4 address; an AAAA record identifies an IPv6 address. A CNAME points to another name and requires further resolution. Always record the queried hostname and record type. A successful lookup for the parent domain is not a result for every subdomain, and the answer your application sees may differ from the one returned by a command-line utility.
Follow the resolver path
Authoritative servers publish zone data; recursive resolvers cache answers for clients. Changes can remain obscured by cached positive or negative answers. Inspect the response code and TTL as well as the address. If a local proxy returns synthetic addresses, investigate its own mapping and upstream DNS settings before declaring the public zone wrong.
DNS does not forward every protocol
Pointing a name at a reverse proxy does not automatically make all TCP and UDP protocols reachable. A CDN's ordinary HTTPS proxy and a direct address record offer different network paths. After checking DNS, verify the actual transport and port from the intended client network. That second test catches problems a correct address alone cannot reveal.
At the terminal
dig example.com A
dig example.com AAAA
dig example.com CNAME
getent ahosts example.com