Judgement rules — status code, keywords, response time & DNS

Each check is one real HTTP request, evaluated in order:

#The judgement chain

Network: DNS resolution, TCP connect, TLS handshake — any failure here fails the check (the error type is labeled separately).
Status code: 2xx required by default; redirects are followed and the final status is what counts.
Response time: over the site's configured timeout = failure; the detail page also shows the long-term trend.
Page content: a hit on a "must not contain" keyword → failure; a missing "must contain" keyword → failure; a recognized framework error page (PHP Fatal, database connection failure, framework exception pages — about 15 kinds) → failure.

Once consecutive failures reach the site's consecutive-failure threshold → judged Incident, an incident is recorded and alerts fire.

#Filling in keywords

Must contain: a word that's always present when the page is healthy, like a footer copyright or a heading.
Must not contain: an error marker such as Fatal error or Error establishing a database connection.
Keyword matching scans the full page text; framework error detection works independently of keywords — see Page error detection.

#DNS verification

On the site detail page you can declare the "expected IPs / records". During a check the authoritative answer is compared against the IP actually connected to — hijacked resolution or changed records are treated as failures. For a new domain that hasn't propagated yet, an unresolvable lookup is only flagged as a hint, not a violation.

← Site monitoring