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Definitions and explainers: monitoring concepts in plain language.
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What Is a Silent Failure in Software Systems?
A failure that produces no error signal. The system reports health while something that should have happened did not.
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What Is an Uptime SLA?
A contractual availability commitment backed by service credits. 99.9% allows nearly nine hours of downtime a year.
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What Is a Cron Job?
A command scheduled to run at fixed times by the cron daemon. The five-field syntax has barely changed since 1987.
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What Is a Webhook?
An HTTP request one system sends to a URL you provide, when something happens. The term was coined in 2007.
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What Is Domain Expiry Monitoring?
Tracking domain registration expiry. There is a recovery window after expiry, but it gets expensive, then impossible.
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What Is SSL Certificate Monitoring?
Checking expiry, chain validity and hostname coverage on TLS certificates. Maximum lifetimes dropped to 200 days in March 2026.
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What Is Credential Expiry Monitoring?
Tracking when API keys, tokens and certificates expire, because nothing in your system emits a signal before they do.
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What Is Business Flow Monitoring?
Tracking whether a defined sequence of events completes in order for one specific record, while hundreds of others run at the same time.
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What Is a Grace Period in Monitoring?
A buffer between a missed deadline and an alert. Set it too low and you get false alarms, too high and you learn late.
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What Is Heartbeat and Cron Monitoring?
Your job calls the monitor instead of the monitor calling your job. Missing check-ins become the alert.
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What Is Webhook Monitoring?
Verifying that webhook events actually arrive and get processed, rather than trusting the sending provider's delivery dashboard.
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What Is a Dead Man's Switch?
A control that acts when the operator stops responding. In software, it means alerting on the absence of a signal rather than the presence of an error.