ERR_NAME_NOT_RESOLVED troubleshooting

ERR_NAME_NOT_RESOLVED means the browser could not turn the hostname into an IP address. It is a DNS failure, not a server failure: the site may be perfectly healthy, but the name lookup never returned the address, so the browser never made a connection. The wording varies by browser (Chrome shows ERR_NAME_NOT_RESOLVED, others say the server's DNS address could not be found), but the meaning is the same, and the fix is a DNS investigation.

Read the meaning

Two things that look similar need different handling:

• Name not resolved: the DNS lookup returned nothing for the hostname.
• Connection refused or timed out: the lookup succeeded but the server did not answer.

The message itself names the layer. When it says the name failed, the problem is almost always in DNS configuration or propagation, not in the server. Rarely it is a typo or a single browser rule.

Separate the layer

Run the lookup against different resolvers to say whether the failure is global, DNS-provider, or local:

nslookup example.com
nslookup example.com 1.1.1.1
nslookup example.com 8.8.8.8

The critical comparison is public resolver against your configured resolver. If 1.1.1.1 and 8.8.8.8 both resolve the name but your machine's usual DNS does not, the record is published and your local or router DNS is stale or misconfigured. If every resolver fails the lookup, the record is not published at all.

Test the likely causes in order

1. Typo or wrong host: check the address you typed, and that a subdomain such as www matches what the DNS zone actually lists.
2. DNS server setting: a Windows machine pointed at a no-longer-valid DNS IP, or a router forwarding queries to a shut-down resolver, fails local lookups while public resolvers succeed. Set the adapter to automatic or a public resolver and re-test.
3. Missing or wrong record: the hostname you need has no A or AAAA record, or it points at a name that does not resolve. Confirm the record exists at the DNS provider and that its value is a real IP.
4. Nameservers not set up: a domain whose nameservers point at DNS hosts that do not serve the zone returns nothing to everyone. Verify the nameservers at the domain and that each authoritative server actually answers (see the DNS servers reference).
5. Not propagated: if you changed records recently, some resolvers may still hold the old period. TTL explains how long resolvers cache a record, so a just-created record can fail for a short window with some resolvers while others serve it (see DNS propagation).

When the record exists but one resolver fails

Flush the local cache and test again after making the change:

• Windows: ipconfig /flushdns
• macOS: sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder
• Avoid relying on the router's resolver for the test; query a public DNS directly.

The same failure can be a blocklist: some corporate or public resolvers filter certain domains. The DNS server not responding article covers the resolver-side case, and the general site not loading guide orders the whole diagnostic before you touch code.

The finish line

When nslookup example.com and nslookup example.com 8.8.8.8 both return an A or AAAA record, the name is resolved and the error is gone on your machine. If the domain still fails for other users, the record was probably just changed, so allow propagation to finish and re-test against a public resolver rather than reporting a fault to your host. If the name is genuinely absent from the zone, add the record at your DNS provider, wait for TTL to pass, and confirm it resolves globally before calling the site live.