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Question 478 of 1,786

Data Ingestion and Transformation →hardMultiple ChoiceObjective-mapped

DEA-C01 Data Ingestion and Transformation Practice Question

This DEA-C01 practice question tests your understanding of data ingestion and transformation. 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 that process data from Amazon RDS for MySQL and load it into Amazon S3. The job runs daily and processes incremental changes using the JDBC connection. Recently, the job has been failing with a 'Communications link failure' error. The RDS instance is in a private subnet. Which step should the engineer take first to diagnose the issue?

Clue words in this question

Noticing these words before you look at the options changes how you read each choice.

Clue: "first"
Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.

A
Verify that the IAM role used by Glue has the correct permissions to access RDS.
Why wrong: Permissions are not indicated by 'Communications link failure'.
B
Change the Glue job type from Spark to Python shell.
Why wrong: Job type does not resolve network errors.
C
Check the security group and network ACL rules for the RDS instance and the Glue connection.
Network misconfiguration is the most common cause of link failure.
D
Check that the JDBC driver is compatible with the Glue version.
Why wrong: Driver compatibility does not cause intermittent link failures.

Full breakdown with real-world context →

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

✓

Check the security group and network ACL rules for the RDS instance and the Glue connection.

The 'Communications link failure' error typically indicates a network connectivity issue between AWS Glue and the RDS instance. Since the RDS instance is in a private subnet, the Glue job must be able to reach it via a VPC endpoint or a Glue connection that uses network configuration. Checking the security group (inbound rules for the RDS instance allowing traffic from Glue's elastic network interfaces) and network ACLs (ensuring ephemeral ports are open) is the first logical step to diagnose connectivity.

Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✗
Verify that the IAM role used by Glue has the correct permissions to access RDS.
Why it's wrong here
Permissions are not indicated by 'Communications link failure'.
✗
Change the Glue job type from Spark to Python shell.
Why it's wrong here
Job type does not resolve network errors.
✓
Check the security group and network ACL rules for the RDS instance and the Glue connection.
Why this is correct
Network misconfiguration is the most common cause of link failure.
Clue confirmation
The clue word "first" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Check that the JDBC driver is compatible with the Glue version.
Why it's wrong here
Driver compatibility does not cause intermittent link failures.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates often jump to IAM permissions or JDBC driver issues first, but the 'Communications link failure' error is a classic network connectivity symptom that requires checking security groups and network ACLs before anything else.

Detailed technical explanation

How to think about this question

AWS Glue uses elastic network interfaces (ENIs) in the VPC specified in the Glue connection to reach RDS. The security group attached to the RDS instance must allow inbound traffic on port 3306 (MySQL) from the security group used by Glue's ENIs, and the network ACLs must allow outbound traffic back to Glue on ephemeral ports (1024-65535). A common subtlety is that if the Glue connection is not configured with the correct subnet and security group, the ENIs may not be placed in a subnet with a route to the RDS instance, causing the connection to fail.

KKey Concepts to Remember

Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.

TExam Day Tips

Watch for words such as best, first, most likely and least administrative effort.
Review why wrong options are wrong, not only why the correct option is correct.

Key takeaway

Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

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.

Visual reference

Quick reference

AWS S3 Storage Class Comparison

Storage Class	Min Duration	Retrieval	Use Case
S3 Standard	None	Immediate	Frequently accessed data
S3 Standard-IA	30 days	Immediate	Infrequent access, rapid retrieval
S3 One Zone-IA	30 days	Immediate	Non-critical infrequent data
S3 Intelligent-Tiering	None	Immediate–hours	Unknown or changing access patterns
S3 Glacier Instant	90 days	Milliseconds	Archive with instant retrieval
S3 Glacier Flexible	90 days	Minutes–hours	Archive, flexible retrieval
S3 Glacier Deep Archive	180 days	Hours	Long-term compliance archive

What to study next

Got this wrong? Here's your next step.

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

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FAQ

Questions learners often ask

What does this DEA-C01 question test?

Data Ingestion and Transformation — This question tests Data Ingestion and Transformation — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: Check the security group and network ACL rules for the RDS instance and the Glue connection. — The 'Communications link failure' error typically indicates a network connectivity issue between AWS Glue and the RDS instance. Since the RDS instance is in a private subnet, the Glue job must be able to reach it via a VPC endpoint or a Glue connection that uses network configuration. Checking the security group (inbound rules for the RDS instance allowing traffic from Glue's elastic network interfaces) and network ACLs (ensuring ephemeral ports are open) is the first logical step to diagnose connectivity.

What should I do if I get this DEA-C01 question wrong?

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

Are there clue words in this question I should notice?

Yes — watch for: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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