The correct answer is to apply a log transformation to the target variable. This action directly addresses heteroscedasticity in regression, where the variance of residuals increases with predicted values—a classic sign of non-constant error spread. By taking the natural log of house prices, the model compresses the scale of large values, stabilizing variance and often linearizing relationships between features and the target, which reduces RMSE. On the AWS Certified Machine Learning Specialty MLS-C01 exam, this scenario tests your understanding of diagnostic plots and remedial measures for regression assumptions; a common trap is to confuse heteroscedasticity with overfitting or outliers. Remember that when residuals fan out like a cone, log the target to bring it home—think "log to flatten the spread."
MLS-C01 Modeling Practice Question
This MLS-C01 practice question tests your understanding of modeling. 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 data scientist is building a regression model to predict house prices. The dataset includes features such as square footage, number of bedrooms, year built, and location. After training a linear regression model, the data scientist notices that the residuals have a clear pattern when plotted against predicted values: they increase with predicted values. The model also has high RMSE. Which action should the data scientist take to improve the model?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Apply a log transformation to the target variable.
Option C is correct because a pattern in residuals indicates non-linearity, and transforming the target variable (e.g., log transformation) can stabilize variance and linearize relationships. Option A is wrong because adding interaction terms may not fix heteroscedasticity. Option B is wrong because removing outliers is not the root cause. Option D is wrong because regularization reduces overfitting but does not address non-linearity.
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.
✗
Remove outliers from the dataset.
Why it's wrong here
Outliers may contribute to the pattern but the pattern suggests a systematic issue, not outliers.
✗
Use L1 regularization (Lasso) to reduce overfitting.
Why it's wrong here
Regularization addresses overfitting, not the non-linear pattern in residuals.
✓
Apply a log transformation to the target variable.
Why this is correct
Log transformation can stabilize variance and linearize the relationship, reducing the residual pattern.
Related concept
Static NAT maps one inside address to one outside address.
✗
Add interaction terms between features.
Why it's wrong here
Interaction terms capture feature interactions but do not address the residual pattern indicating non-linearity.
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 company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
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 MLS-C01 NAT questions on configuration and troubleshooting.
Modeling — This question tests Modeling — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Apply a log transformation to the target variable. — Option C is correct because a pattern in residuals indicates non-linearity, and transforming the target variable (e.g., log transformation) can stabilize variance and linearize relationships. Option A is wrong because adding interaction terms may not fix heteroscedasticity. Option B is wrong because removing outliers is not the root cause. Option D is wrong because regularization reduces overfitting but does not address non-linearity.
What should I do if I get this MLS-C01 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 MLS-C01 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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This MLS-C01 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the MLS-C01 exam.
Question Discussion
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