DOP-C02 Exam Dumps : AWS Certified DevOps Engineer - Professional

The current design colocates the web tier, database, and cache on the same EC2 instances. This causes resource contention and makes it difficult to scale each layer independently. The correct solution is to separate these concerns into independently scalable managed services.

Option D uses an Application Load Balancer (ALB) in front of an Auto Scaling group for the web application. ALB is designed for HTTP/HTTPS traffic, supports path-based and host-based routing, and can spread load evenly across multiple instances and Availability Zones, eliminating the issue where one instance is overloaded.

The database is migrated to Amazon Aurora with Multi-AZ , which provides high availability, automated failover, and managed backups. Aurora offloads database management and ensures consistent performance.

For caching, Option D introduces Amazon ElastiCache for Redis , a managed in-memory cache that is purpose-built for low-latency reads, independent scaling, and high availability through replication and clustering.

Option A and C misuse NLB for HTTP traffic or for Redis exposure and introduce unnecessary complexity. Option B keeps Redis on EC2 (via NLB + ASG in a single AZ), which reduces availability and does not leverage managed caching.

Thus, Option D best separates tiers and improves performance and availability.

AWS Control Tower provides an integrated governance framework that combines both preventive controls, implemented as Service Control Policies at the OU level, and detective controls, implemented as AWS Config rules applied across all enrolled accounts. Control Tower automatically applies these guardrails to all accounts in enrolled OUs. When new accounts are provisioned through Account Factory, they are automatically enrolled in the assigned OU and receive all applicable preventive and detective controls immediately without manual intervention. Option A uses only SCPs, covering only preventive controls without built-in detective capabilities. Option C requires manually updating stack sets when new accounts are created and does not provide preventive controls via SCPs. Option D provides only detective controls through Config rules with no preventive guardrails. Control Tower is the only option that natively handles both control types and automatically governs newly created accounts.

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 Turn off cross-zone load balancing on the ALB ' s target group:

Cross-zone load balancing distributes traffic evenly across all registered targets in all enabled Availability Zones. Turning this off will ensure that each target group only handles requests from its respective Availability Zone.

To disable cross-zone load balancing:

Go to the Amazon EC2 console.

Navigate to Load Balancers and select the ALB.

Choose the Target Groups tab, select the target group, and then select the Group details tab.

Click on Edit and turn off Cross-zone load balancing.

 Use Amazon Route 53 Application Recovery Controller to start a zonal shift away from the Availability Zone:

Amazon Route 53 Application Recovery Controller provides the ability to control traffic flow to ensure high availability and disaster recovery.

By using Route 53 Application Recovery Controller, you can perform a zonal shift to redirect traffic away from the unhealthy Availability Zone.

To start a zonal shift:

Configure Route 53 Application Recovery Controller by creating a cluster and control panel.

Create routing controls to manage traffic shifts between Availability Zones.

Use the routing control to shift traffic away from the affected Availability Zone.