The correct answer is that the schema of the source data has changed and is not reflected in the Data Catalog. This Glue schema mismatch error, specifically the "cannot resolve column" message, occurs because AWS Glue compares the column names in your Spark DataFrame against the schema registered in the Data Catalog; when a column present in your code is missing from the catalog’s definition—often due to a rename, drop, or addition in the underlying S3 files—the job fails with an AnalysisException. On the AWS Certified Data Engineer Associate DEA-C01 exam, this question tests your understanding of schema evolution and the importance of keeping the Data Catalog in sync with source data, a common trap being that candidates confuse this with data type mismatches or permission errors. To remember: think "Catalog must match the columns you call"—if the column name isn’t in the catalog, Glue can’t resolve it.
DEA-C01 Data Operations and Support Practice Question
This DEA-C01 practice question tests your understanding of data operations and support. 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.
A company uses AWS Glue to run ETL jobs on a schedule. Recently, a job failed with the error: 'AnalysisException: cannot resolve '`column_name`' given input columns: ...'. The job reads from an Amazon S3 source that has a schema defined in the AWS Glue Data Catalog. 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 schema of the source data has changed and is not reflected in the Data Catalog.
Option B is correct because the error indicates a missing column. This typically happens when the source data schema changes (e.g., column renamed or dropped) but the Data Catalog schema is not updated. Option A is incorrect because an incompatible IAM role would cause a different error (e.g., AccessDenied). Option C is incorrect because a corrupted file would cause a read error, not a schema resolution error. Option D is incorrect because the 'cannot resolve' error is about column names, not data types.
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 schema of the source data has changed and is not reflected in the Data Catalog.
Why this is correct
Schema evolution without updating catalog causes column resolution errors.
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 source data file is corrupted and cannot be parsed.
Why it's wrong here
Corrupted files cause parse errors, not schema resolution errors.
✗
The IAM role associated with the Glue job does not have permissions to read the S3 bucket.
Why it's wrong here
Permission errors would be AccessDenied, not AnalysisException.
✗
The data type of the column in the source does not match the Data Catalog definition.
Why it's wrong here
Data type mismatches cause type errors, not 'cannot resolve' errors.
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 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 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 DEA-C01 NAT questions on configuration and troubleshooting.
Data Operations and Support — This question tests Data Operations and Support — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: The schema of the source data has changed and is not reflected in the Data Catalog. — Option B is correct because the error indicates a missing column. This typically happens when the source data schema changes (e.g., column renamed or dropped) but the Data Catalog schema is not updated. Option A is incorrect because an incompatible IAM role would cause a different error (e.g., AccessDenied). Option C is incorrect because a corrupted file would cause a read error, not a schema resolution error. Option D is incorrect because the 'cannot resolve' error is about column names, not data types.
What should I do if I get this DEA-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 DEA-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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