The answer is that the DataFrame does not have a column named 'age'. This is the most likely cause because the error message explicitly states the column 'age' is missing from the input data, which only contains columns [id, name, salary]; AWS Glue ETL jobs fail at runtime when a transformation or mapping references a column that does not exist in the schema. On the AWS Certified Machine Learning Specialty MLS-C01 exam, this scenario tests your ability to read error logs and distinguish between schema mismatch, schema evolution, and data type issues—a common trap is confusing a missing column error with a type conversion error or assuming schema evolution will automatically add the column. Remember the memory tip: "If the column name isn't in the schema, Glue will scream."
MLS-C01 Exploratory Data Analysis Practice Question
This MLS-C01 practice question tests your understanding of exploratory data analysis. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
Network Topology
A data scientist ran an AWS Glue ETL job that failed with the error shown. What is the most likely cause?
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
✓
The DataFrame does not have a column named 'age'
Option C is correct because the error indicates the column 'age' is not found in the input data, which has columns [id, name, salary]. Option A is wrong because the error is about a missing column, not a mismatch. Option B is wrong because schema evolution would add column, not cause error. Option D is wrong because there is no indication of data type issue.
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.
✗
The CSV file has a header mismatch
Why it's wrong here
Incorrect: The error specifically says column 'age' cannot be resolved, not a mismatch.
✓
The DataFrame does not have a column named 'age'
Why this is correct
Correct: The error states 'age' is not in the input columns.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
✗
The schema is evolving incorrectly
Why it's wrong here
Incorrect: Schema evolution would add missing columns.
✗
The data type of 'age' is incompatible
Why it's wrong here
Incorrect: The error is about column existence, not type.
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 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. NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated. 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.
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.
Exploratory Data Analysis — This question tests Exploratory Data Analysis — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: The DataFrame does not have a column named 'age' — Option C is correct because the error indicates the column 'age' is not found in the input data, which has columns [id, name, salary]. Option A is wrong because the error is about a missing column, not a mismatch. Option B is wrong because schema evolution would add column, not cause error. Option D is wrong because there is no indication of data type issue.
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.
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?
Static NAT maps one inside address to one outside address.
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Question Discussion
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