The answer is that the IAM role assumed by Kinesis Data Firehose in each account lacks the necessary permissions to write to the cross-account Amazon OpenSearch Service domain. This is the most likely cause of failed deliveries because Firehose operates under an IAM role in its own account, and to deliver logs to a destination in a different account, that role must explicitly include a trust policy and an IAM policy granting `es:ESHttpPut` and `es:ESHttpPost` actions on the target OpenSearch domain’s ARN. On the AWS Certified DevOps Engineer Professional DOP-C02 exam, this scenario tests your understanding of cross-account resource-based policies and IAM delegation, a common trap where engineers focus on network or data stream configurations instead of the fundamental permission boundary. A frequent memory tip is to think of Firehose as a delivery driver: it needs a key (the IAM role) that works at the destination building (the OpenSearch domain), not just a key for its own garage.
DOP-C02 Monitoring and Logging Practice Question
This DOP-C02 practice question tests your understanding of monitoring and logging. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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 DevOps engineer is tasked with centralizing logs from multiple AWS accounts into a single Amazon OpenSearch Service domain. The engineer sets up Amazon Kinesis Data Firehose to deliver logs from each account to the OpenSearch domain. However, some accounts show failed deliveries in the Firehose console. Which configuration is MOST likely causing the failures?
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 IAM role assumed by Firehose in each account does not have permissions to write to the cross-account OpenSearch domain
Option B is correct because each account must have an IAM role that grants Firehose cross-account access to the OpenSearch domain's destination. Option A is wrong because CloudWatch Logs subscription is not required. Option C is wrong because Kinesis Data Streams is not needed. Option D is wrong because S3 bucket permissions are not relevant for direct Firehose-to-OpenSearch delivery.
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 IAM role assumed by Firehose in each account does not have permissions to write to the cross-account OpenSearch domain
Why this is correct
Firehose needs an IAM role with sts:AssumeRole and es:HttpPut permissions for the destination OpenSearch domain.
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 accounts do not have a CloudWatch Logs subscription filter to send logs to Firehose
Why it's wrong here
Logs can be sent to Firehose directly, not necessarily via CloudWatch subscription.
✗
The Kinesis Data Streams used as the Firehose source is not encrypted
Why it's wrong here
Encryption is not required for Firehose delivery.
✗
The OpenSearch domain's access policy does not allow access from the S3 bucket used by Firehose
Why it's wrong here
Firehose delivers directly to OpenSearch, not via S3.
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 DOP-C02 NAT questions on configuration and troubleshooting.
Monitoring and Logging — This question tests Monitoring and Logging — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: The IAM role assumed by Firehose in each account does not have permissions to write to the cross-account OpenSearch domain — Option B is correct because each account must have an IAM role that grants Firehose cross-account access to the OpenSearch domain's destination. Option A is wrong because CloudWatch Logs subscription is not required. Option C is wrong because Kinesis Data Streams is not needed. Option D is wrong because S3 bucket permissions are not relevant for direct Firehose-to-OpenSearch delivery.
What should I do if I get this DOP-C02 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 DOP-C02 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.
About these practice questions
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These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A DevOps engineer is tasked with setting up a centralized logging solution for a multi-account AWS environment. Which service should be used to aggregate logs from multiple accounts?
easy
A.Amazon S3 with cross-region replication
B.AWS CloudTrail with organization trails
✓ C.Amazon CloudWatch Logs with cross-account subscription
D.AWS Config with aggregated compliance rules
Why C: Amazon CloudWatch Logs can aggregate logs across accounts using cross-account subscriptions with a central destination (e.g., Kinesis or Lambda). Option C is correct. Option A is incorrect because S3 is a storage service, not for real-time aggregation. Option B is incorrect as CloudTrail is for API activity, not application logs. Option D is incorrect because AWS Config is for configuration compliance.
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This DOP-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 DOP-C02 exam.
Question Discussion
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