A developer is intermittently receiving HTTP 400 ThrottlingException errors when calling the CloudWatch API and no data is returned on failure. What best practice should be applied first to mitigate this?

The correct answer is to retry the call with exponential backoff. AWS services, including CloudWatch, have API call limits to ensure fair usage and service stability. When these limits are exceeded, a ThrottlingException occurs. Implementing exponential backoff means retrying the API call after increasing delays, which helps to avoid overwhelming the service and allows the request to succeed once the throttling period passes. This is a standard best practice for handling transient errors in distributed systems. Contacting AWS Support for a limit increase is a reactive measure for persistent, high-volume needs, not the first step for intermittent throttling. Using the AWS CLI to get metrics doesn't address the underlying API throttling issue; it's just another way to make the same API calls. Analyzing applications to remove the API call is an extreme measure that might not be feasible or necessary, as the API call itself might be essential.