What is downtime?
Downtime is time when a website or service can't be used: it doesn't answer, answers with an error, or is too slow to be usable.
In more detail
Downtime can be total (nothing answers), partial (the home page works but checkout fails) or a slowdown so severe that visitors give up. It is planned when it is announced in advance for maintenance, and unplanned otherwise.
How quickly downtime is noticed depends on the check interval and on how a failure is confirmed. A monitor that alerts on one failed check is fast but noisy; one that waits for a second failed check is slightly slower and far more trustworthy.
Worked example
A site stops answering at 10:02. A monitor checking every 5 minutes sees the failure at 10:05 and checks again at 10:10. The second failure confirms the outage, so the owner is emailed at about 10:10, eight minutes after it started. A single failed check at 10:05 on its own would not trigger an alert.
That is how OwlHound works: checks every 5 minutes, and an email only when the next round fails too.
See also
Related terms: Uptime and Incident. Free tool: Is it down?. How OwlHound helps: Website uptime monitoring. All terms: monitoring glossary.
Frequently asked questions
What is the difference between downtime and an outage?
They are often used as synonyms. Strictly, an outage is one event, and downtime is the total time lost across all outages in a period.
What causes website downtime?
Most often an expired domain or certificate, a hosting or provider problem, a bad update or deploy, or traffic the server can't handle. Our guide on what causes website downtime goes through them.
How quickly can downtime be detected?
Within one check interval, plus the time to confirm it. With 5-minute checks and a confirming round, that is usually under 10 minutes.
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