How to Troubleshoot DNS Problems
DNS turns names into IP addresses, so when it fails nothing else can work — the browser never learns where to connect. Most DNS problems fall into a handful of causes you can check in order.
Know the record types
- A — maps a name to an IPv4 address.
- AAAA — maps a name to an IPv6 address.
- CNAME — an alias pointing one name at another.
- MX — mail servers for the domain.
- NS — the authoritative name servers for the domain.
- TXT — free-form text, used for SPF, DKIM, and domain verification.
Common causes of DNS failure
- Missing or wrong record — the A/AAAA record doesn't exist or points at the wrong IP.
- Expired domain — registration lapsed, so the whole zone stops resolving.
- Name server misconfiguration — NS records point at servers that don't host the zone.
- Propagation lag — a recent change hasn't cleared old caches yet.
- Local cache / resolver — your machine or ISP resolver has a stale or broken cached answer.
Isolate the fault step by step
- Confirm the domain resolves at all — query the A record. No answer anywhere means a record or registration problem.
- Check the NS records — verify the domain points at the name servers you expect.
- Compare from multiple locations — if some resolve and some don't, it's propagation or a regional cache, not a missing record.
- Flush your local DNS cache and retry — this rules out a stale answer on your side.
- For mail issues, check MX and the relevant TXT (SPF/DKIM) records specifically.
Reading the result
If a lookup resolves everywhere with the right values, DNS is healthy and the problem is elsewhere (server, network, or application). If it fails only in some places, you're looking at propagation or a caching issue that time or a flush will fix. If it fails everywhere, the record or the domain itself is the problem — fix it at the authoritative source.
Frequently asked questions
Why does my browser say "server DNS address could not be found"?
The resolver couldn't turn the domain into an IP — usually a missing A record, an expired domain, a name server misconfiguration, or a stale local cache. Query the record from multiple locations to see which.
How do I fix stale DNS on my own machine?
Flush your operating system's DNS cache and restart the browser. If a public resolver still serves the old value, it's inside the record's TTL window and will update when that expires.