The answer is that attaching the Lambda function to a VPC is the most likely cause of performance degradation, specifically due to network latency for S3 API calls. When a Lambda function is configured within a default VPC, it loses its default internet access and must route traffic through an Elastic Network Interface (ENI) in a private subnet, which introduces significant overhead for any request that leaves the VPC, including calls to S3. This is a classic trap on the SAP-C02 exam: candidates often overlook that Lambda functions in a VPC cannot reach S3 directly via the public endpoint without a NAT gateway or VPC endpoint, and the default configuration adds latency that slows processing. The exam tests your understanding of how Lambda’s network architecture changes when placed inside a VPC, and the common mistake is assuming the VPC has no impact on S3 access. Remember the mnemonic: “VPC Lambda = ENI overhead, S3 calls go slow.”
SAP-C02 Continuous Improvement for Existing Solutions Practice Question
This SAP-C02 practice question tests your understanding of continuous improvement for existing solutions. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 using AWS Lambda functions to process files uploaded to an S3 bucket. Recently, the processing time has increased significantly. A solutions architect notices that the Lambda functions are using the default VPC configuration. What is the MOST likely cause of the performance degradation?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Lambda function is attached to a VPC, causing network latency for S3 API calls.
Option B is correct because Lambda functions in a VPC use an Elastic Network Interface (ENI) in a private subnet, which can add latency for internet-bound requests. Options A, C, and D do not directly cause increased processing time.
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.
✗
Lambda function is using too much memory.
Why it's wrong here
Memory affects CPU, not network latency.
✓
Lambda function is attached to a VPC, causing network latency for S3 API calls.
Why this is correct
Lambda in a VPC uses ENIs and routes through NAT for internet access, adding latency.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
S3 bucket has versioning enabled, causing extra overhead.
Why it's wrong here
Versioning does not significantly impact processing time.
✗
S3 bucket is in a different region.
Why it's wrong here
Cross-region S3 access adds latency, but the question does not mention region mismatch.
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 SAP-C02 subnetting questions on CIDR, address ranges, and subnet selection.
Continuous Improvement for Existing Solutions — This question tests Continuous Improvement for Existing Solutions — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Lambda function is attached to a VPC, causing network latency for S3 API calls. — Option B is correct because Lambda functions in a VPC use an Elastic Network Interface (ENI) in a private subnet, which can add latency for internet-bound requests. Options A, C, and D do not directly cause increased processing time.
What should I do if I get this SAP-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 SAP-C02 subnetting questions on CIDR, address ranges, and subnet selection.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
CIDR notation defines the prefix length.
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