The answer is to create a CloudWatch Logs subscription filter that invokes a Lambda function for redaction. This is correct because subscription filters enable real-time streaming of log events to AWS Lambda, where you can run custom code to detect and redact sensitive data in CloudWatch Logs as it arrives, before it is stored long-term. On the AWS Certified SysOps Administrator Associate SOA-C02 exam, this scenario tests your understanding of real-time log processing versus post-hoc analysis; a common trap is choosing CloudWatch Logs Insights, which only queries historical data and cannot modify logs in flight. Another pitfall is assuming Kinesis Data Firehose alone handles redaction, but it requires a Lambda function for custom transformations. For memory, remember the mantra: “Subscribe, transform, redact—Lambda is the real-time fact.”
SOA-C02 Security and Compliance Practice Question
This SOA-C02 practice question tests your understanding of security and compliance. 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 SysOps administrator notices that an Amazon CloudWatch Logs log group is growing rapidly and suspects that an EC2 instance is sending sensitive data to the logs. What is the most effective way to detect and redact sensitive data in real-time?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create a CloudWatch Logs subscription filter that invokes a Lambda function for redaction.
Option D is correct because CloudWatch Logs subscription filters can send logs to Lambda for real-time processing, including redaction. Option A is wrong because CloudWatch Logs Insights is for querying, not real-time redaction. Option B is wrong because Kinesis Data Firehose can transform data but requires a Lambda function for custom redaction. Option C is wrong because S3 event notifications are not real-time for log streams.
Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
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 CloudWatch Logs Insights to query and mask sensitive data.
Why it's wrong here
CloudWatch Logs Insights is for analysis, not real-time redaction.
✗
Enable S3 event notifications to trigger a Lambda function for redaction.
Why it's wrong here
This would require storing logs in S3 first, adding latency.
✓
Create a CloudWatch Logs subscription filter that invokes a Lambda function for redaction.
Why this is correct
CloudWatch Logs subscription filters can stream logs to Lambda in real-time for processing.
Send logs to Amazon Kinesis Data Firehose and use Lambda for redaction.
Why it's wrong here
Kinesis Data Firehose can use Lambda for transformation, but it's not the most direct integration.
Common exam traps
Common exam trap: usable hosts are not the same as total addresses
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Detailed technical explanation
How to think about this question
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
KKey Concepts to Remember
CIDR notation defines the prefix length.
Block size helps identify subnet boundaries.
Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
The required host count determines the smallest suitable subnet.
TExam Day Tips
→Write the block size before choosing the subnet.
→Check whether the question asks for hosts, subnets or a specific address range.
→Do not confuse /24, /25, /26 and /27 host counts.
Key takeaway
Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Real-world example
How this comes up in practice
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
What to study next
Got this wrong? Here's your next step.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related SOA-C02 subnetting questions on CIDR, address ranges, and subnet selection.
Security and Compliance — This question tests Security and Compliance — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Create a CloudWatch Logs subscription filter that invokes a Lambda function for redaction. — Option D is correct because CloudWatch Logs subscription filters can send logs to Lambda for real-time processing, including redaction. Option A is wrong because CloudWatch Logs Insights is for querying, not real-time redaction. Option B is wrong because Kinesis Data Firehose can transform data but requires a Lambda function for custom redaction. Option C is wrong because S3 event notifications are not real-time for log streams.
What should I do if I get this SOA-C02 question wrong?
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related SOA-C02 subnetting questions on CIDR, address ranges, and subnet selection.
What is the key concept behind this question?
CIDR notation defines the prefix length.
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Question Discussion
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