SOA-C03 practice question: Network cost optimization

Networking and Content Delivery A free question from our original SOA-C03 practice exam. Try it, then open the answer to see why each option is right or wrong.

A regional bank's statement-generation instances run in private subnets and write about 40 TB a month to Amazon S3 buckets in the same Region through a NAT gateway. The monthly bill shows high NAT gateway data processing charges. Security policy requires that this traffic stay off the public internet. What should a CloudOps engineer do to reduce the cost while meeting the policy?

Choose one answer.

A. Replace the NAT gateway with a NAT instance on a large EC2 instance type to avoid per-gigabyte processing charges.
B. Turn on S3 Transfer Acceleration so that the uploads use the AWS edge network instead of the NAT gateway.
C. Create an S3 gateway VPC endpoint and add it to the route tables of the private subnets.
D. Move the NAT gateway to the same Availability Zone as most of the instances to remove the processing charges.

Show the answer and explanation

Answer: C

A. Wrong: A NAT instance avoids the processing charge, but the bank would run, patch and scale it, and it becomes a single point of failure. A gateway endpoint removes the charge with no instances. Learn more: NAT gateways (opens in a new tab)
B. Wrong: Transfer Acceleration speeds up long-distance transfers through edge locations and adds its own charges. The instances would still reach it through the NAT gateway. Learn more: Configuring fast, secure file transfers using Amazon S3 Transfer Acceleration (opens in a new tab)
C. Right: Correct. A gateway endpoint routes S3 traffic privately within the AWS network, and it has no hourly or data processing charge. The NAT gateway no longer handles the S3 traffic. Learn more: Gateway endpoints for Amazon S3 (opens in a new tab)
D. Wrong: Keeping traffic in one Availability Zone avoids cross-AZ data transfer charges. The NAT gateway still charges for every gigabyte it processes, so the main cost stays. Learn more: Amazon VPC pricing (opens in a new tab)

Explanation

NAT gateways charge for each gigabyte they process, which grows quickly for bulk S3 traffic. A gateway VPC endpoint for S3 is free and keeps traffic on the AWS network, so moving S3 traffic onto it removes most of the charge. Interface endpoints for S3 also exist but have hourly and per-gigabyte charges.

SOA-C03 practice question: Network cost optimization

Explanation

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