The answer is Amazon Route 53, because it enables blue/green deployment on AWS by using weighted DNS routing to control traffic distribution between environments. By adjusting the weight values on Route 53 DNS records, you can gradually shift a percentage of user traffic from the blue (current) environment to the green (new) environment, allowing for a seamless cutover with minimal downtime and an instant rollback path by simply resetting the weights. On the AWS Certified SAP on AWS Specialty PAS-C01 exam, this question tests your understanding of how to implement deployment strategies without relying on load balancers or application-level changes; a common trap is choosing Elastic Load Balancing, but Route 53 is the correct service here because it operates at the DNS level, decoupling traffic routing from the compute layer. A helpful memory tip: think of Route 53 as the “traffic cop” that uses weights to slowly let the green cars onto the road while keeping the blue cars ready to pull back in.
PAS-C01 Migration Practice Question
This PAS-C01 practice question tests your understanding of migration. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 is migrating a web application to AWS and wants to use a blue/green deployment strategy to minimize downtime. Which AWS service should be used to route traffic between the blue and green environments?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "minimum / minimize"
Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Amazon Route 53
Amazon Route 53 is correct because it supports weighted DNS routing, which allows you to shift traffic gradually between blue and green environments by adjusting the weight values for DNS records. This enables a blue/green deployment strategy with minimal downtime, as Route 53 can route a percentage of traffic to the new environment while keeping the old environment active for rollback.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Amazon CloudFront
Why it's wrong here
CloudFront is a content delivery network, not suitable for routing traffic between environments.
✗
AWS Global Accelerator
Why it's wrong here
Global Accelerator improves performance but does not provide native blue/green routing capabilities.
✗
Application Load Balancer (ALB)
Why it's wrong here
ALB distributes traffic to targets within a single environment, not between blue and green.
✓
Amazon Route 53
Why this is correct
Route 53 supports weighted routing policy to shift traffic between blue and green environments.
Clue confirmation
The clue word "minimum / minimize" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse load balancers (ALB) with traffic routing services, assuming an ALB can directly manage blue/green environments, but ALB requires Route 53 or similar DNS-level routing to split traffic between separate environments.
Detailed technical explanation
How to think about this question
Route 53's weighted routing policy uses DNS responses with a weight value (0-255) per record; the probability of a client receiving a particular record is weight / sum of all weights. This allows fine-grained traffic shifting, such as starting with 10% to green and 90% to blue, then gradually adjusting to 100% green. However, DNS caching by clients and resolvers (based on TTL) can cause delayed propagation, so setting a low TTL (e.g., 60 seconds) is critical for rapid cutover.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. 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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Migration — This question tests Migration — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Amazon Route 53 — Amazon Route 53 is correct because it supports weighted DNS routing, which allows you to shift traffic gradually between blue and green environments by adjusting the weight values for DNS records. This enables a blue/green deployment strategy with minimal downtime, as Route 53 can route a percentage of traffic to the new environment while keeping the old environment active for rollback.
What should I do if I get this PAS-C01 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "minimum / minimize". Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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