The answer is to use the `aws s3 sync` command, as it is the most efficient way to resume an interrupted S3 upload. This command works by comparing the source directory with the destination bucket, automatically identifying and transferring only the files that are missing or have been modified since the last run, which directly addresses the partial failure from a `RequestTimeout` error without re-uploading already transferred data. On the AWS Certified Developer Associate DVA-C02 exam, this scenario tests your understanding of idempotent operations and the `sync` command’s ability to handle large-scale transfers efficiently—a common trap is choosing `aws s3 cp` with a recursive flag, which lacks the built-in comparison logic and would waste time re-uploading everything. For a quick memory tip, think of `sync` as “smart sync”—it only sends what’s missing, saving time and bandwidth after any interruption.
DVA-C02 Troubleshooting and Optimization Practice Question
This DVA-C02 practice question tests your understanding of troubleshooting and optimization. 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 developer runs a script that uses the AWS CLI to copy a large number of files from an on-premises server to an S3 bucket. The copy operation fails partway through with a 'RequestTimeout' error. What is the MOST efficient way to resume the copy and ensure all files are transferred?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use the aws s3 sync command to synchronize the source directory with the S3 bucket.
The `aws s3 sync` command is the most efficient way to resume the copy because it automatically compares the source directory with the destination S3 bucket and transfers only the files that are missing or have been modified. This avoids re-uploading already transferred files, directly addressing the partial failure without manual intervention or unnecessary overhead.
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.
✗
Delete the S3 bucket and restart the copy operation.
Why it's wrong here
Unnecessarily deletes already uploaded files.
✓
Use the aws s3 sync command to synchronize the source directory with the S3 bucket.
Why this is correct
Sync only uploads files that are new or changed.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use the cp command with the --recursive flag to copy the remaining files.
Why it's wrong here
Does not automatically skip already copied files.
✗
Increase the --cli-read-timeout value in the AWS CLI configuration and retry the original command.
Why it's wrong here
May avoid timeout but still re-uploads existing files.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse `cp --recursive` with `sync`, assuming both can resume a copy, but only `sync` performs a differential comparison to avoid re-uploading already transferred files.
Detailed technical explanation
How to think about this question
The `aws s3 sync` command uses a combination of object metadata (ETag, last modified timestamp) to determine which files need to be transferred, making it idempotent and ideal for resuming interrupted transfers. Under the hood, it issues `ListObjectsV2` requests against the S3 bucket and compares the results with the local directory listing, then performs parallel `PutObject` calls only for the delta. This is particularly useful in scenarios where large datasets are being migrated incrementally or when network reliability is a concern, as it minimizes redundant data transfer.
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.
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.
Troubleshooting and Optimization — This question tests Troubleshooting and Optimization — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use the aws s3 sync command to synchronize the source directory with the S3 bucket. — The `aws s3 sync` command is the most efficient way to resume the copy because it automatically compares the source directory with the destination S3 bucket and transfers only the files that are missing or have been modified. This avoids re-uploading already transferred files, directly addressing the partial failure without manual intervention or unnecessary overhead.
What should I do if I get this DVA-C02 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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