SAP-C02 Question 347
Select 2A company is running a multi-tier web application hosted in AWS. The application involves an Amazon EC2-based web tier, an Amazon RDS database, and an Amazon S3 bucket for storing static content. The company has noticed unexpected spikes in its data transfer costs. To optimize costs, you are tasked with identifying the scenarios that incur additional data transfer charges. Which of the following scenarios will result in additional data transfer costs? (Select TWO.)
- A
An Amazon EC2 instance in a private subnet downloads data from an Amazon S3 bucket located in the same AWS Region.
- B
An Amazon EC2 instance in one Availability Zone communicates with another Amazon EC2 instance in a different Availability Zone within the same AWS Region.
- C
An Amazon EC2 instance in one AWS Region transfers data to an Amazon RDS instance in the same Region.
- D
Users download static content from an Amazon S3 bucket using the public Internet.
- E
An Amazon EC2 instance communicates with an Amazon RDS instance in a different AWS Region.
Show answer and explanation
Correct answers: B, D
Explanation
AWS data transfer costs can vary depending on the source and destination of the data. Data transfer within the same Region (e.g., between EC2 and S3 or RDS) is usually free or minimal, but transferring data across Availability Zones or out to the Internet incurs additional charges. In this scenario, inter-AZ data transfer and data transfers from S3 to the Internet are the two situations that specifically lead to higher costs as per the provided options.
- A. Incorrect.
No additional data transfer charges apply when an EC2 instance accesses S3 within the same AWS Region, as this qualifies for free data transfer.
- B. Correct.
Data transfer between EC2 instances in different Availability Zones within the same Region incurs inter-AZ data transfer charges.
- C. Incorrect.
Data transfer within a single AWS Region between EC2 and RDS does not incur additional data transfer costs.
- D. Correct.
Data transfer from Amazon S3 to the Internet incurs data transfer out charges, which contribute to additional costs.
- E. Incorrect.
Data transfer between an EC2 instance and an RDS instance in different AWS Regions incurs inter-Region data transfer costs. However, this option is not correct as it explicitly mentions inter-region transfer, and the correct answers focus on other cost scenarios.