A video transcoding service on EC2 should page the team only when two independent conditions hold together on one instance: CPU stays above 80 percent and outbound network throughput stays above a set level. Which CloudWatch capability should the engineer use to combine the two signals?
Show answer and explanation
Answer: A
A composite alarm evaluates other alarms and enters ALARM only when its Boolean rule is satisfied, such as one alarm AND another. It produces a single state for paging, which cuts noise from any one noisy signal. Each child alarm keeps its own threshold and period, so the engineer can reuse them elsewhere.
Why the other options are wrong
- B. An anomaly detection band learns the normal pattern of one metric and alarms on deviation from it. It does not combine two separate thresholds, so it cannot express the requirement that both conditions hold together.
- C. A metric filter turns matching log lines into a numeric metric. It is useful for counting events in logs, but it does not join CPU and network signals or require both conditions to be true at once.
- D. Contributor Insights ranks the top contributors to a pattern in log events, such as the busiest instances. It produces rankings rather than an alarm state, so it cannot gate a page on two conditions.