What DNS is, and why it fails before your server does
01The short answer#
DNS is the internet's phone book. Before a browser can load your site, it asks DNS which IP address your domain points to. If that answer is wrong, slow or missing, the visitor gets an error and your server never even sees the request.
That's what makes DNS outages so confusing. The server is healthy, the logs are quiet, every dashboard inside your network is green, and customers still can't reach you.
02How it breaks#
- A record changed by mistake, or still pointing at a server you shut down.
- The domain expired, and the whole zone stopped answering.
- Your DNS provider has an outage of its own.
- A change is still spreading, so some visitors get the old address and some the new one.
03How UpControl catches it#
UpControl checks your site from outside your network, exactly like a visitor's browser, starting with the DNS lookup. When your name stops resolving, the incident says so in its title: "DNS error", not a vague "down".
Every check also times the lookup apart from the connection, the TLS handshake and the server's wait, so a slow DNS provider shows up as its own bar on your Response speed card. And your domain's expiry date sits on every website check, on every plan.