What DNS is doing
Browsers do not connect to “example.com”. They look up addresses (A and AAAA records) and then open a TCP connection. If DNS fails, the site looks down even when the web servers are healthy.
Common failures
NXDOMAIN means the name does not exist in DNS — expired domain, typo, or a zone that was removed. No address records means the name exists but has nothing to connect to. A resolver failure means the DNS servers did not answer correctly, which can be the domain’s DNS host or your own resolver.
Safe things to try
If only one site fails and DownSpotter also reports NXDOMAIN, the name is probably wrong or expired. If DownSpotter resolves DNS and you do not, try another network or a well-known public resolver in your OS settings. Flushing the local DNS cache is reasonable; changing random router firmware is not.
- Confirm the spelling of the domain.
- See whether DownSpotter can resolve DNS from our side.
- Try cellular vs Wi-Fi to rule out a local resolver.
- If many sites fail, reboot the router and review DNS settings.