AWS Certified Associate SAA-C03 Book

The ALB must be in a public subnet to receive internet traffic. The EC2 instances and the RDS database should be in private subnets to prevent direct internet access, minimizing the attack surface. This aligns with AWS security best practices for web application architectures.

Reference Extract:

" Internet-facing ALBs should be placed in public subnets; EC2 instances and RDS databases should be in private subnets to restrict direct internet access. "

Source: AWS Certified Solutions Architect – Official Study Guide, Network Security and Design section.

Large binary objects are usually more cost-effective inAmazon S3than in a relational database. AWS S3 documentation describes S3 as highly durable object storage, and AWS storage guidance commonly uses a database to holdmetadatawhile S3 stores the objects themselves. Moving the documents out of the Oracle database reduces expensive database storage growth and can improve database performance by shrinking the amount of blob data managed inside the DB engine. The existing database can continue to store metadata and relational records, preserving application structure while improving cost efficiency and resilience. The other options either increase database cost further or shift to a much bigger redesign than needed.

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Amazon CloudFront is a global content delivery network (CDN) that caches and distributes content to users with low latency. By setting the existing ALB as the origin, CloudFront can cache dynamic and static content closer to users worldwide, improving performance and reducing the load on the application servers. This is the most cost-optimized and AWS-recommended way to globally serve dynamic content for web applications.

Reference Extract:

" CloudFront accelerates delivery of both static and dynamic content, reducing latency and offloading origin resources by caching content at edge locations. "

Source: AWS Certified Solutions Architect – Official Study Guide, CloudFront and Global Application section.

The correct answer isCbecause the existing application usesNFS storagefor an image cache that isa few terabytes in size, and the company wants themost cost-effective cloud alternative.Amazon EFS One Zoneis a managed file storage service that supports theNFS protocol, which allows the application to continue using a familiar file-based interface with minimal architectural change. Because this is acache, not primary durable data, storing it in aOne Zonefile system is a cost-optimized choice compared with a Regional EFS deployment.

Amazon EFS is designed for shared file storage and can scale to multiple terabytes automatically. It avoids the operational overhead of managing EC2 instances and local disks for cache storage. It is also better aligned than object storage for workloads that already expect direct NFS semantics. The application can mount the EFS file system and use it as the cache backend without redesigning around object APIs or in-memory caching models.

Option A is incorrect becauseElastiCache Memcachedis an in-memory cache and is typically much more expensive for multi-terabyte cache data than file storage. Option B is incorrect because using EC2 instance store volumes creates significant management overhead and the cache would be lost whenever instances are terminated or replaced. Option D is incorrect becauseAmazon S3 Express One Zoneis object storage, not NFS storage, and would require application redesign and additional metadata management in DynamoDB.

AWS storage guidance recommends matching file-based workloads to managed file services. For a largeNFS-based cache,Amazon EFS One Zoneis the most cost-effective and operationally simple solution.