A CloudWatch alarm is in the ALARM state, but nobody received the notification. What should you check?
Show answer and explanation
Answer: D
An alarm only publishes to its actions when actions are enabled on the alarm, and the message then depends on SNS actually delivering it. A subscription that is still pending confirmation, an endpoint that bounced, or a topic policy that denies cloudwatch.amazonaws.com will all break delivery while the alarm state looks perfectly normal. Checking the alarm's action configuration and the subscription status separates the two halves of the path.
Why the other options are wrong
- A. Recreating the alarm does not fix a disabled action or an unconfirmed subscription, so the new alarm fails the same way.
- B. Changing the threshold alters when the alarm fires, not whether its notification is delivered.
- C. Disabling the alarm suppresses actions further and discards the state you were trying to diagnose.
Exam tip. ALARM with no notification means check actions enabled first, then SNS subscription confirmation.