The answer is to create a target tracking scaling policy using the custom metric as the target. This is the most efficient approach because target tracking automatically adjusts the EC2 Auto Scaling group capacity to keep the custom metric—such as the number of active users—at or near a specified target value, eliminating the need to manually define thresholds or complex step adjustments. On the AWS Certified Solutions Architect Professional SAP-C02 exam, this scenario tests your understanding of when to use target tracking versus step or scheduled scaling policies; a common trap is overcomplicating the solution with Lambda or step scaling when a simple target tracking policy suffices. Remember that target tracking is ideal for variable, unpredictable workloads where you only need to specify a target metric value, while step scaling is better for metrics with known, fixed thresholds. Memory tip: think “set it and forget it” for target tracking—you define the target, and AWS handles the math.
SAP-C02 Continuous Improvement for Existing Solutions Practice Question
This SAP-C02 practice question tests your understanding of continuous improvement for existing solutions. 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 runs a web application on EC2 instances in an Auto Scaling group. The application receives a variable workload. The company wants to scale based on a custom metric that tracks the number of active users. What is the MOST efficient way to achieve this?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create a target tracking scaling policy using the custom metric as the target.
Option B is correct because a target tracking scaling policy automatically adjusts capacity based on the metric. Option A is wrong because step scaling is more complex and less efficient. Option C is wrong because scheduled scaling is for predictable patterns. Option D is wrong because Lambda is not needed for this.
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.
✗
Use a scheduled scaling policy to add or remove instances based on historical usage patterns.
Why it's wrong here
Scheduled scaling is for predictable patterns, not variable workloads.
✗
Use AWS Lambda to periodically evaluate the custom metric and adjust the desired capacity via API calls.
Why it's wrong here
This adds complexity and is less efficient than built-in scaling policies.
✗
Create a step scaling policy that uses CloudWatch alarms based on the custom metric.
Why it's wrong here
Step scaling requires defining steps and is less efficient than target tracking.
✓
Create a target tracking scaling policy using the custom metric as the target.
Why this is correct
Target tracking automatically adjusts capacity to maintain the target metric value.
Related concept
Static NAT maps one inside address to one outside address.
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
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
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: Create a target tracking scaling policy using the custom metric as the target. — Option B is correct because a target tracking scaling policy automatically adjusts capacity based on the metric. Option A is wrong because step scaling is more complex and less efficient. Option C is wrong because scheduled scaling is for predictable patterns. Option D is wrong because Lambda is not needed for this.
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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Question Discussion
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