The correct answer is Use Amazon S3 as the target. Enable an S3 Lifecycle policy to transition the logs to S3 Standard-Infrequent Access (S3 Standard-IA) after 90 days.

Storing VPC Flow Logs in Amazon S3 allows for durable, scalable storage, and integration with lifecycle management. By keeping logs in the S3 Standard storage class for the first 90 days, they remain readily accessible. After 90 days, a lifecycle policy can transition them to S3 Standard-IA, which is more cost-effective for infrequently accessed data while still offering millisecond retrieval. This approach balances performance with cost optimization.

Use Amazon CloudWatch as the target. Set the CloudWatch log group with an expiration of 90 days would delete the logs after 90 days, which violates the requirement for long-term intermittent access.

Use Amazon Kinesis as the target. Configure the Kinesis stream to always retain the logs for 90 days is incorrect because Kinesis is designed for real-time data streaming and short-term retention, not long-term log storage or intermittent access. It also incurs higher costs for extended retention.

Use AWS CloudTrail as the target. Configure CloudTrail to save to an Amazon S3 bucket, and enable S3 Intelligent-Tiering is misleading. CloudTrail is not a valid target for VPC Flow Logs, and Intelligent-Tiering is best suited for unpredictable access patternsnot for predictable transitions after a fixed period like 90 days.

Why this question matters: It evaluates your ability to architect cost-effective, long-term storage solutions for audit and compliance logs using AWS-native tools like S3 and lifecycle management. Understanding storage classes and retention strategies is essential for cloud efficiency and compliance.

Tip: If you see a predictable pattern of high-to-low access over time, S3 lifecycle policies paired with Standard and Standard-IA classes are a smart choice. Dont confuse log storage targetsCloudWatch and CloudTrail are not interchangeable with VPC Flow Logs.

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