DVA-C02 Deployment Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✓

  An ALB with two target groups, one for blue and one for green.

  Why this is correct

  An Application Load Balancer (ALB) with two distinct target groups, one designated for the "blue" (current production) environment and another for the "green" (new version) environment, is the standard and most effective architecture for blue/green deployments. The ALB acts as a stable entry point, and its listener rules can be precisely updated to shift traffic from the blue target group to the green target group after successful validation, enabling zero-downtime deployments and immediate rollback capabilities. This setup allows both versions to run concurrently, facilitating thorough testing of the new version before promoting it to full production traffic.

• ✗

  An ALB with a single target group and an Amazon CloudFront distribution.

  Why it's wrong here

  An ALB with a single target group cannot facilitate a blue/green deployment because this strategy inherently requires two separate, concurrently running environments (blue and green) to switch traffic between. While an Amazon CloudFront distribution can improve performance and security by caching content and acting as a CDN, it operates at a layer above the ALB and does not provide the necessary traffic shifting or environment management capabilities required for a blue/green deployment. CloudFront would simply route requests to the *single* ALB target group, offering no mechanism to switch between old and new application versions.

• ✗

  An ECS service discovery namespace.

  Why it's wrong here

  An ECS service discovery namespace, typically implemented with AWS Cloud Map, is designed to help microservices locate and communicate with each other dynamically within an application. While crucial for complex microservices architectures, service discovery does not directly provide the traffic management and environment switching mechanisms fundamental to a blue/green deployment strategy. It enables services to find endpoints, but it doesn't orchestrate the deployment of new application versions or manage the controlled traffic shift between distinct blue and green environments.

• ✗

  A Network Load Balancer (NLB) with a single target group.

  Why it's wrong here

  A Network Load Balancer (NLB) with a single target group is insufficient for a blue/green deployment because it lacks the ability to simultaneously host and switch traffic between two distinct application versions. NLBs operate at Layer 4 (TCP/UDP) and primarily forward traffic based on IP address and port, offering less flexibility for application-level routing compared to ALBs. While an NLB *could* be part of a more complex blue/green setup involving multiple NLBs or IP-based routing to multiple target groups, a single target group fundamentally prevents the necessary concurrent existence and controlled traffic shifting between blue and green environments.