DNS Errors and Troubleshooting

Start with the resolver answer

DNS troubleshooting starts before HTTP. If the hostname does not resolve, the browser cannot reach the web server, so changing WordPress, nginx, or PHP will not help. Separate local resolver cache from authoritative DNS records before you change nameservers or A records.

Authoritative DNS vs recursive cache

Authoritative nameservers hold the source records for the domain. Recursive resolvers, such as ISP resolvers or public DNS services, cache those answers for a time. If one resolver still has an old answer, compare it against the authoritative nameserver instead of changing every record repeatedly.

Records to check

Check A and AAAA records for direct IP targets, CNAME records for host aliases, MX records for mail, NS records for delegation, and TTL values for expected cache windows. For browser-facing errors, the linked Chrome and DNS pages help separate a local browser profile problem from a domain-wide resolver issue.

Resolver comparison workflow

Compare at least three answers before changing production records: the authoritative nameserver, a public resolver, and the affected user's resolver if available. If authoritative DNS has the right answer but one recursive resolver is stale, wait for TTL or flush that resolver where possible. If authoritative DNS is wrong, fix the zone at the active DNS provider rather than editing DNS at an old registrar or inactive host.

Glossary

A and AAAA records point a hostname to IPv4 or IPv6 addresses. A CNAME points one hostname at another hostname. NS records say which nameservers are authoritative. TTL is the cache window. NXDOMAIN means the resolver could not find the requested name.