- A
Amazon Managed Blockchain
Why wrong: Managed Blockchain provides decentralized distributed blockchain networks — QLDB is a centralized ledger database for trusted applications that don't need decentralization.
- B
Amazon RDS with point-in-time recovery
Why wrong: RDS PITR restores databases to a prior state but doesn't provide an immutable cryptographically verifiable audit trail — changes can be overwritten and are not hash-chained.
- C
Amazon QLDB (Quantum Ledger Database)
QLDB provides an immutable, cryptographically verifiable journal — every data change is recorded with a hash, making the complete history tamper-evident.
- D
AWS CloudTrail
Why wrong: CloudTrail records API events with log file integrity validation — QLDB is specifically designed for application data transaction history, not API audit logging.
Quick Answer
The answer is Amazon QLDB (Quantum Ledger Database). This service is the correct choice because it provides an immutable, cryptographically verifiable transaction log that records every change to application data in an append-only journal, using cryptographic hashing to chain entries together so the complete history cannot be altered or deleted. On the AWS Certified Cloud Practitioner CLF-C02 exam, this question tests your understanding of specialized database services beyond traditional relational or NoSQL options, often appearing as a distractor against Amazon DynamoDB or Amazon RDS—but remember, only QLDB offers a true immutable ledger with a built-in verifiable history. A common trap is confusing QLDB with Amazon Managed Blockchain, which focuses on decentralized networks across multiple parties, whereas QLDB is a centralized ledger for a single trusted authority. For a quick memory tip, think “QLDB = Queryable Ledger Database” where the “L” stands for “Ledger” and the “I” in “Immutable” reminds you that data cannot be changed once written.
CLF-C02 Cloud Technology and Services Practice Question
This CLF-C02 practice question tests your understanding of cloud technology and services. 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.
Which AWS service provides an immutable, cryptographically verifiable transaction log for tracking the complete history of changes to application data?
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
Amazon QLDB (Quantum Ledger Database)
Amazon QLDB (Quantum Ledger Database) provides an immutable, append-only journal that records every change to application data. It uses cryptographic hashing to chain entries together, creating a verifiable history that cannot be altered or deleted, which is exactly what the question describes.
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.
- ✗
Amazon Managed Blockchain
Why it's wrong here
Managed Blockchain provides decentralized distributed blockchain networks — QLDB is a centralized ledger database for trusted applications that don't need decentralization.
- ✗
Amazon RDS with point-in-time recovery
Why it's wrong here
RDS PITR restores databases to a prior state but doesn't provide an immutable cryptographically verifiable audit trail — changes can be overwritten and are not hash-chained.
- ✓
Amazon QLDB (Quantum Ledger Database)
Why this is correct
QLDB provides an immutable, cryptographically verifiable journal — every data change is recorded with a hash, making the complete history tamper-evident.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
AWS CloudTrail
Why it's wrong here
CloudTrail records API events with log file integrity validation — QLDB is specifically designed for application data transaction history, not API audit logging.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse AWS CloudTrail's immutable logging of API calls with an application-level immutable transaction log, but CloudTrail does not track application data changes or provide a cryptographically verifiable ledger.
Detailed technical explanation
How to think about this question
QLDB uses a Merkle tree structure to hash each block of journal entries, linking them to the previous block's hash, which ensures tamper evidence. The journal is append-only, meaning data can only be added, not modified or deleted, and users can verify the integrity of the entire history using the built-in digest API. In a real-world scenario, a financial services company might use QLDB to maintain an immutable record of all transactions for regulatory compliance, where any attempt to alter past entries would break the cryptographic chain.
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 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. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. 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.
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 CLF-C02 question test?
Cloud Technology and Services — This question tests Cloud Technology and Services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Amazon QLDB (Quantum Ledger Database) — Amazon QLDB (Quantum Ledger Database) provides an immutable, append-only journal that records every change to application data. It uses cryptographic hashing to chain entries together, creating a verifiable history that cannot be altered or deleted, which is exactly what the question describes.
What should I do if I get this CLF-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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Last reviewed: Jun 11, 2026
This CLF-C02 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 CLF-C02 exam.
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