AWS CLF-C02: Cloud Technology and Services Practice Questions

AWS Lambda is the best fit. It is a serverless, event-driven compute service that can be triggered directly by S3 events (e.g., ObjectCreated). It requires no server management, scales automatically per invocation, and is billed only for the milliseconds of execution time — perfect for short, event-driven tasks like image resizing. EC2 with Auto Scaling requires provisioning and managing instances; the team would need to poll S3 for new files rather than receiving automatic triggers. ECS on EC2 launch type involves running containers on EC2 instances that the team must manage, which violates the no-server-management requirement. Elastic Beanstalk is a PaaS for long-running applications; it still provisions EC2 instances underneath and is not event-driven by nature.

Amazon EFS is a fully managed, scalable file system that can be mounted simultaneously by multiple EC2 instances, making it ideal for shared file access within a VPC. Amazon EBS is block storage that attaches to a single EC2 instance at a time (Multi-Attach is available only for io1/io2 volumes in limited scenarios and is not the standard recommendation for general shared access). Amazon S3 is object storage, not a traditional file system that can be mounted and used for concurrent file-level reads and writes the way applications typically expect. AWS Storage Gateway is a hybrid storage service used to connect on-premises environments to AWS cloud storage, not a native shared file system for EC2 instances.

Amazon SQS FIFO (First-In, First-Out) Queue guarantees that messages are processed exactly once and in the exact order they are sent, which matches the requirement for ordered processing by exactly one consumer (the fulfillment system). Amazon SNS with a standard topic is a pub/sub service designed to fan out messages to multiple subscribers — it does not guarantee ordering and is not ideal for a single-consumer, order-sensitive flow. Amazon SQS Standard Queue delivers messages at least once and does not guarantee ordering, so it would not satisfy the strict ordering requirement. Amazon EventBridge with a default event bus is an event routing service used for event-driven architectures across multiple services/targets; it is not designed for guaranteed ordered, single-consumer queuing.

Amazon RDS with Multi-AZ deployment automatically provisions and maintains a synchronous standby replica in a different Availability Zone. In the event of a primary instance failure, RDS automatically fails over to the standby, minimizing downtime. It also handles automated backups and patching, meeting all stated requirements. Amazon RDS with Read Replicas improves read performance by creating asynchronous copies, but Read Replicas are not designed for automatic failover — they serve read traffic only. Amazon DynamoDB with global tables is a NoSQL solution for multi-region replication, not a MySQL replacement with Multi-AZ failover. Amazon Aurora with a single instance is a managed relational database but without a standby, it does not provide the automatic Multi-AZ failover the company requires.

AWS Budgets allows the company to set a defined monthly cost budget and configure alert thresholds (e.g., 80% of budgeted amount, or when forecasted spend is projected to exceed the threshold). AWS Budgets alert actions integrated with Amazon SNS automatically send notifications (emails, SMS, etc.) when those thresholds are breached, fulfilling the alerting requirement. AWS Cost Explorer provides visualization and analysis of past spending and Savings Plans recommendations, but it does not enforce budgets or send automated alerts based on thresholds. Amazon CloudWatch billing alarms can alert on actual charges but have more limited forecasting capability compared to AWS Budgets and require manual configuration of the threshold as an absolute dollar value; AWS Budgets is the purpose-built service for this use case. AWS Trusted Advisor cost optimization checks identify ways to reduce costs (e.g., idle resources) but do not monitor spending against a defined budget or send budget threshold alerts. AWS Cost and Usage Report exports raw billing data to S3 for analysis but does not provide alerting or budget enforcement functionality.