It's Probably DNS - Can You Dig It? - Duende Software

- **Incorrect A/AAAA Records:** The most fundamental issue. Your domain's A (IPv4) or AAAA (IPv6) record might point to an outdated or inaccurate server IP address. - **Missing or Incorrect CNAME Records:** If you use a CNAME (Canonical Name) record—often for setting up a subdomain to point to a hosting server or content delivery network (CDN)—an incorrect target can cause clients to misroute traffic. - **TTL (Time to Live) Cache Problems:** When you change a DNS record, it takes time to propagate across the Internet. If administrators set the TTL value too high, old, incorrect records might be stubbornly cached by local resolvers, proxies, and even user browsers, making it seem like your change didn't take effect. - **Mismatched NS (Name Server) Records:** The domain registrar is responsible for adding the correct NS records (and potential A glue records) to the TLD zone. (e.g., AWS Route 53, Cloudflare). If records are mismatched, you will never be able to query for the correct DNS records.