The correct answer is to use Amazon Route 53 weighted routing policies to shift traffic gradually and to migrate session state to ElastiCache or DynamoDB for continuity. This combination works because a DNS-level traffic shift allows you to control the flow between blue and green environments without requiring a native blue/green feature from the load balancer, while offloading session state to a dedicated caching or database layer ensures that user sessions persist even as instances are swapped out. On the AWS Certified Solutions Architect Professional SAP-C02 exam, this question tests your understanding of how to implement blue green deployments for stateful web applications, a common scenario where stateless design principles must be applied to legacy systems. A frequent trap is assuming Elastic Load Balancing natively handles blue/green swaps, but it does not—you must orchestrate the shift via Route 53 or an Application Load Balancer’s weighted target groups. Another pitfall is setting a high TTL on DNS records, which delays traffic switching and defeats the purpose of reducing downtime. Memory tip: think “DNS shift, state offload” to remember the two key actions for stateful blue/green deployments.
SAP-C02 Continuous Improvement for Existing Solutions Practice Question
This SAP-C02 practice question tests your understanding of continuous improvement for existing solutions. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company has a stateful web application running on Amazon EC2 instances. They want to implement blue/green deployments to reduce downtime. Which TWO actions should the company take? (Choose TWO.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Migrate session state to Amazon ElastiCache or DynamoDB.
Option B is correct because a swap at the DNS level (e.g., Route 53 weighted records or blue/green with ALB) is key. Option D is correct because for stateful apps, migrating session state to ElastiCache or DynamoDB ensures continuity. Option A is wrong because ELB does not manage blue/green natively. Option C is wrong because setting TTL high delays traffic switching. Option E is wrong because deregistering instances from the old group is done after testing, not immediately.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Migrate session state to Amazon ElastiCache or DynamoDB.
Why this is correct
Decoupling session state from instances enables seamless blue/green.
Related concept
Static NAT maps one inside address to one outside address.
✗
Use an Elastic Load Balancer (ELB) to manage the blue and green environments.
Why it's wrong here
ELB itself doesn't manage blue/green; you need separate target groups and switch traffic.
✓
Use Amazon Route 53 weighted routing policies to shift traffic gradually.
Why this is correct
Weighted routing allows gradual traffic shift from blue to green.
Related concept
Static NAT maps one inside address to one outside address.
✗
Set a high TTL on the DNS record to prevent caching issues.
Why it's wrong here
High TTL slows traffic transition; low TTL is preferred.
✗
Immediately deregister the blue instances from the load balancer after deployment.
Why it's wrong here
Should be done after verifying green, not immediately.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
How this comes up in practice
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
Got this wrong? Here's your next step.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related SAP-C02 NAT questions on configuration and troubleshooting.
Continuous Improvement for Existing Solutions — This question tests Continuous Improvement for Existing Solutions — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Migrate session state to Amazon ElastiCache or DynamoDB. — Option B is correct because a swap at the DNS level (e.g., Route 53 weighted records or blue/green with ALB) is key. Option D is correct because for stateful apps, migrating session state to ElastiCache or DynamoDB ensures continuity. Option A is wrong because ELB does not manage blue/green natively. Option C is wrong because setting TTL high delays traffic switching. Option E is wrong because deregistering instances from the old group is done after testing, not immediately.
What should I do if I get this SAP-C02 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related SAP-C02 NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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