Amazon Web Services AWS Certified Associate SAA-C03 New Questions

To achieve high availability for the website, two key actions should be taken:

Amazon RDS for MySQL Multi-AZ: By migrating the database to an RDS for MySQL Multi-AZ deployment, the database becomes highly available. Multi-AZ provides automatic failover from the primary database to a standby replica in another Availability Zone, ensuring database availability even in the case of an AZ failure.

Application Load Balancer and Auto Scaling: Deploying an Application Load Balancer (ALB) in front of the EC2 instances ensures that traffic is evenly distributed across the instances. Configuring an Auto Scaling group to run EC2 instances across multiple Availability Zones ensures that the application remains available even if one instance or one AZ becomes unavailable. This setup enhances fault tolerance and improves reliability.

Why Not Other Options?:

Option A (Internet Gateway per AZ): Internet Gateways are region-wide resources and do not need to be provisioned per Availability Zone. This option does not contribute to high availability.

Option C (DynamoDB + Auto Scaling): DynamoDB would require changes to the application code to switch from MySQL, which is not possible per the question's constraints.

Option D (DataSync): AWS DataSync is used for data transfer and synchronization, not for achieving high availability for a database.

AWS References:

Amazon RDS Multi-AZ Deployments- Explanation of how Multi-AZ deployments work in Amazon RDS.

Application Load Balancing- Details on how to configure and use ALB for distributing traffic across multiple instances.

The Application Load Balancer (ALB) supports sticky sessions (session affinity) using application cookies. AWS WAF integrates natively with ALB to provide Layer 7 protection at the same endpoint.

From AWS Documentation:

“You can enable sticky sessions for your Application Load Balancer target groups to ensure that a user’s requests are consistently routed to the same target. AWS WAF integrates with Application Load Balancer to protect your web applications from common exploits.”

(Source: Elastic Load Balancing User Guide & AWS WAF Developer Guide)

Why C and E are correct:

C: ALB operates at Layer 7 (HTTP/HTTPS), supports sticky sessions, and can serve as a public endpoint.

E: AWS WAF can be directly associated with the ALB to inspect traffic and enforce rules.Together, they fulfill both the security and session affinity requirements.

Why others are incorrect:

A: Network Load Balancer doesn’t support session affinity.

B: Gateway Load Balancer is used for virtual appliances, not web applications.

D: Using EIPs bypasses load balancing and WAF integration.

EC2 instances in private subnets cannot access the internet unless there is a NAT gateway or a NAT instance configured.

“To enable instances in a private subnet to connect to the internet or other AWS services, you can use a NAT gateway or NAT instance.”

— NAT Gateways – Amazon VPC

In this use case:

EC2 instances are in private subnets

They need to call external APIs (internet access)

The most operationally efficient and secure method is to place a NAT Gateway in a public subnet and update the route table for private subnets to route internet-bound traffic through it.

Incorrect Options:

A: Private subnets don’t support public IPs.

C: VPC peering doesn’t help reach the public internet.

D: Interface endpoints are for private connectivity to AWS services, not external APIs.

AWS advises using serverless event-driven processing to minimize operational burden and scale automatically with demand. Amazon SQS can be directly configured as an event source for AWS Lambda. With this setup, Lambda polls the queue, invokes the function, and processes messages without requiring the customer to manage infrastructure. Scaling is automatic, based on the volume of messages in the queue. Option A (increasing instance size) still leaves scaling and management challenges. Option B reduces cost when idle but does not address scaling. Option D requires manual triggering and does not meet continuous processing requirements. Migrating the script to Lambda (C) fully eliminates the need for instance management, providing scalability, reliability, and reduced operational overhead.