Launching an RDS instance in AWS - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Configuration

intermediate

Identify the correct AWS CLI command to launch a MySQL RDS instance

Which AWS CLI command will successfully launch a MySQL RDS instance named mydbinstance with 20GB storage in the us-east-1 region?

A aws rds create-db-instance --db-instance-identifier mydbinstance --db-instance-class db.t3.micro --engine mysql --allocated-storage 20 --region us-east-1

B aws rds launch-db-instance --db-instance-identifier mydbinstance --db-instance-class db.t3.micro --engine mysql --allocated-storage 20 --region us-east-1

C aws rds create-db-instance --db-instance-identifier mydbinstance --db-instance-class db.t3.micro --engine postgres --allocated-storage 20 --region us-east-1

D aws rds create-db-instance --db-instance-identifier mydbinstance --db-instance-class db.t3.micro --engine mysql --allocated-storage 5 --region us-east-1

💡 Hint

Check the AWS CLI command syntax for creating an RDS instance and verify the engine and storage size.

Option A uses the correct AWS CLI command 'create-db-instance' with the MySQL engine and 20GB storage. Option A uses a non-existent command 'launch-db-instance'. Option A uses the wrong engine 'postgres'. Option A uses insufficient storage (5GB) which is below the minimum for MySQL RDS.

❓ Architecture

intermediate

Choosing the best subnet configuration for a highly available RDS instance

You want to launch an RDS instance that remains available even if one Availability Zone fails. Which subnet configuration should you choose?

A Launch the RDS instance in multiple public subnets in the same Availability Zone.

B Launch the RDS instance in a single public subnet in one Availability Zone.

C Launch the RDS instance in multiple private subnets across different Availability Zones using a DB subnet group.

D Launch the RDS instance in a single private subnet with a NAT gateway.

💡 Hint

Think about how AWS achieves high availability for RDS instances.

Option C is correct because RDS uses a DB subnet group with subnets in multiple Availability Zones to enable Multi-AZ deployments for high availability. Options B and C use a single subnet or AZ, which is not highly available. Option C uses multiple subnets but in the same AZ, so it does not protect against AZ failure.

❓ security

advanced

Securing RDS instance access with least privilege

You want to restrict access to your RDS instance so only your application servers in a specific security group can connect. Which configuration achieves this?

A Set the RDS instance's security group to allow inbound traffic on port 3306 from the application servers' security group.

B Set the RDS instance's security group to allow inbound traffic on port 3306 from 0.0.0.0/0.

C Set the RDS instance's security group to allow inbound traffic on port 3306 from the internet gateway.

D Set the RDS instance's security group to allow inbound traffic on port 3306 from the VPC CIDR block.

💡 Hint

Consider the principle of least privilege and how security groups reference each other.

Option A restricts access to only the application servers by referencing their security group, following least privilege. Option A allows access from anywhere, which is insecure. Option A incorrectly references the internet gateway, which is not a source IP. Option A allows access from the entire VPC, which is broader than needed.

❓ service_behavior

advanced

Understanding RDS Multi-AZ failover behavior

What happens to your RDS instance endpoint during a Multi-AZ failover event?

A The endpoint becomes unavailable until you restart the RDS instance.

B The endpoint DNS automatically points to the standby instance in the other Availability Zone with minimal downtime.

C You must manually update the endpoint to point to the new primary instance after failover.

D The endpoint IP address changes but DNS remains the same, causing connection failures.

💡 Hint

Think about how AWS manages failover to minimize impact on applications.

Option B is correct because AWS RDS automatically updates the DNS endpoint to point to the new primary instance during failover, minimizing downtime. Option B is incorrect because manual intervention is not required. Option B is wrong as the endpoint remains available after failover. Option B is incorrect because the DNS name remains the same and AWS manages IP changes transparently.

✅ Best Practice

expert

Optimizing cost and performance for a production RDS instance

You have a production RDS instance with steady traffic. You want to optimize for cost without sacrificing availability or performance. Which combination of configurations is best?

A Use a Single-AZ deployment with a db.m6g.large instance class and provisioned IOPS storage with autoscaling.

B Use a Single-AZ deployment with a db.t3.micro instance class and magnetic storage.

C Use a Multi-AZ deployment with a db.r5.2xlarge instance class and provisioned IOPS storage without autoscaling.

D Use a Multi-AZ deployment with a db.m6g.large instance class and enable storage autoscaling with General Purpose SSD (gp3).

💡 Hint

Balance availability, instance type, and storage type for cost and performance.

Option D balances cost and performance by using a cost-efficient ARM-based instance (m6g), Multi-AZ for availability, and gp3 storage with autoscaling for performance and cost control. Option D sacrifices availability and performance. Option D uses an expensive instance and storage without autoscaling, increasing cost. Option D sacrifices availability by using Single-AZ.