SOA-C03 practice question: CloudWatch metrics, alarms and dashboards (2 of 3)

Monitoring, Logging, Analysis, Remediation, and Performance Optimization A free question from our original SOA-C03 practice exam. Try it, then open the answer to see why each option is right or wrong.

A ski resort runs a nightly lift-pass reconciliation job on Amazon EC2.

While it runs, the job publishes a custom CloudWatch metric, RecordsProcessed, every minute. If the job crashes, it stops publishing the metric completely. The operations team created an alarm on RecordsProcessed less than 1 for 5 consecutive periods, but when the job crashed last week the alarm stayed in INSUFFICIENT_DATA and nobody was notified.

Which change makes the alarm notify the team when the job stops publishing?

Choose one answer.

A. Set the alarm's missing data treatment to notBreaching so that gaps in the metric are evaluated as normal data points.
B. Set the alarm's missing data treatment to ignore so that the alarm keeps its last state until new data arrives.
C. Set the alarm's missing data treatment to breaching so that every missing data point counts as below the threshold.
D. Increase the alarm period from 1 minute to 1 hour so that at least one data point is always present in each period.

Show the answer and explanation

Answer: C

A. Wrong: notBreaching treats missing points as within the threshold, so the alarm would move to OK during a crash. That is the opposite of what the team needs. Learn more: Configuring how CloudWatch alarms treat missing data (opens in a new tab)
B. Wrong: ignore keeps the current alarm state when data is missing. If the alarm was OK before the crash, it stays OK and nobody is told the job stopped. Learn more: Configuring how CloudWatch alarms treat missing data (opens in a new tab)
C. Right: Correct. With breaching, CloudWatch evaluates missing points as if they cross the threshold. Five minutes with no published data moves the alarm to ALARM and triggers its notification. Learn more: Configuring how CloudWatch alarms treat missing data (opens in a new tab)
D. Wrong: A longer period does not create data when the job is not publishing. After a crash there are still no data points, so the alarm still lacks data to evaluate. Learn more: Alarm evaluation (opens in a new tab)

Explanation

When a metric disappears, the alarm's TreatMissingData setting decides what happens. The default, missing, leads to INSUFFICIENT_DATA when all points are absent. For a heartbeat-style metric where silence means failure, breaching is the right choice, because it turns the absence of data into an alarm.

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Configuring how CloudWatch alarms treat missing data

SOA-C03 practice question: CloudWatch metrics, alarms and dashboards (2 of 3)

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