Developers often debug API failures at the application layer first. A quick DNS check can show whether the hostname resolves before code, TLS, or routing is involved.

Commands to use

dig api.example.com A
dig api.example.com CNAME

Checklist

  1. Check API hostname A/AAAA records.
  2. Check CNAME chains to hosting platforms.
  3. Compare local resolver and public resolver results.
  4. Confirm private DNS is being used when endpoints are internal.

How to use the result

The DNS answer should be compared with the intended source of truth: registrar delegation, DNS provider zone, hosting target, email provider instructions, certificate authority challenge, or internal network documentation. If they do not match, fix the source record before troubleshooting higher layers.