DNS not resolving on Linux

Compare resolver answers, authoritative answers, TTL, direct HTTP checks, and server reachability before changing DNS again.

Safest first command

dig +short example.com A

Before you run this

Expected output: One or more IP addresses, or no answer if the resolver cannot resolve the name.

When not to use it: Do not keep changing DNS records before checking TTL and authoritative nameserver answers.

Expected output example

203.0.113.10

How to read the result

If the expected address appears, DNS may not be the current failure. If answers differ between resolvers or authoritative servers, check TTL and record source before changing more records.

Compare DNS and direct server response

A browser failure can be DNS, TLS, routing, Nginx, or the app. Compare resolver answers and force a direct HTTP check to the expected IP.

dig +short example.com A
dig @1.1.1.1 example.com A +short
curl --resolve example.com:443:203.0.113.10 https://example.com/

Check TTL and authoritative servers

If public resolvers disagree, check whether propagation is still inside TTL or authoritative records differ.

Common causes

Stale resolver cache or TTL delay
Wrong authoritative nameserver
A record and AAAA record disagree
Local resolv.conf or systemd-resolved issue
Server is reachable by IP but virtual host/TLS is wrong

What not to change yet

Do not keep editing DNS records while TTL is still active.
Do not flush only the browser cache and assume DNS changed globally.
Do not ignore IPv6 if AAAA records exist.

platform notes

Distro and service notes

systemd-resolved

resolvectl can show which resolver the host actually uses.

macOS

Use macOS resolver tools and cache-flush guidance for Apple Terminal pages.

Web hosting

Use curl --resolve to separate DNS from the web server response.

supporting commands