If a domain does not resolve, work from registration outward instead of changing random DNS records.
- Confirm the domain registration is active and not expired.
- Check which authoritative nameservers the registrar delegates the domain to.
- Confirm those nameservers respond for the domain.
- At the authoritative DNS provider, verify the required A/AAAA/CNAME records.
- Check whether DNSSEC is enabled and whether the parent DS record matches the current signing keys.
- Allow for cached DNS data when a recent change was made.
NXDOMAIN usually means the requested name does not exist in DNS. SERVFAIL can indicate a nameserver problem or a DNSSEC validation failure. Those two errors point to different troubleshooting paths.
