Free SAA-C03 flashcards

How can an application on Amazon EC2 read from a specific Amazon S3 bucket without any stored long-lived credentials?

Attach an IAM role through an instance profile with a policy scoped to s3:GetObject on that one bucket. The instance metadata service supplies short-lived credentials that rotate automatically, removing static access keys while granting least privilege.

Putting an IAM user's access key and secret in EC2 user data at launch removes static credentials from an application.

User data still injects a long-lived static key that can leak. Relocating the key does not remove it. Use an IAM role via an instance profile so credentials are temporary and rotated automatically.

How can a web tier absorb traffic spikes and stop dropping work when downstream EC2 workers are overwhelmed, with the least operational effort?

Put an Amazon SQS standard queue between the producer and the workers. SQS is a durable, pull-based buffer: producers enqueue messages that persist for the retention period, and workers poll and delete them at their own pace. Bursts are smoothed because messages wait in the queue instead of being dropped when consumers are saturated.

An Application Load Balancer with connection draining will queue surplus requests until a worker is free, so no orders are lost during a spike.

An Application Load Balancer distributes synchronous requests but does not durably buffer them. When no healthy target can respond, requests time out and orders are still lost. Durable buffering needs Amazon SQS, not a load balancer.

In Amazon S3, how do you raise the achievable request rate for a workload hitting HTTP 503 slow-down responses on a single key prefix?

Amazon S3 scales request throughput per key prefix, supporting at least 3,500 PUT and 5,500 GET requests per second on each prefix independently. Concentrating requests on one prefix hits that single ceiling. Spreading keys across many prefixes lets requests run against many prefix limits in parallel, multiplying aggregate throughput without leaving S3.

Enabling Amazon S3 Versioning spreads request load and raises the per-prefix throughput ceiling.

S3 Versioning keeps prior copies of an object for recovery. It does not change how S3 partitions request capacity by prefix, so the throughput ceiling on a hot prefix is unchanged. To raise throughput, distribute keys across multiple prefixes.

Which S3 storage class minimises cost for objects whose per-object access is unpredictable, without retrieval fees or any application change?

Amazon S3 Intelligent-Tiering. It monitors each object individually and shifts it between a frequent-access tier and an infrequent-access tier based on that object's own usage, charging only a small monitoring fee and no retrieval fee. Tiering is transparent to readers, so a mix of hot and cold objects is handled automatically without code or per-object retrieval penalties.

Keeping everything in S3 Standard and relying on volume discounts as the bucket grows minimises cost for unpredictable access.

S3 Standard applies the full frequent-access price to every object, including cold ones that are rarely read. Volume discounts do not change that per-GiB rate enough to optimise a mix of hot and cold data. S3 Intelligent-Tiering moves each object to a cheaper tier automatically when it cools.