Quick Answer
The answer is that NODATA indicates no network traffic was observed for the subnet during the given capture period. This status appears when VPC Flow Logs are actively collecting but the aggregation interval—typically 10 minutes—passes with zero packets flowing through the monitored elastic network interfaces. It is a normal, healthy status, not an error or a delivery failure; the logs are simply reporting an empty window. On the AWS Certified Advanced Networking Specialty ANS-C01 exam, this concept tests your ability to distinguish between NODATA (no traffic) and SKIPDATA (capture or delivery issues), a common trap where engineers mistakenly assume a configuration problem. Remember the memory tip: NODATA = No Traffic At All, while SKIPDATA = Something Kept Interrupting Packet Delivery.
This ANS-C01 practice question tests your understanding of network design. 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 network engineer configured VPC Flow Logs for a subnet to capture all traffic. After reviewing the logs in CloudWatch Logs, they notice that some logs show 'NODATA' for the log-status field. What does 'NODATA' indicate?
No network traffic was observed for the given capture period.
Correct meaning.
The flow log record was skipped due to an internal error.
Why wrong: That's SKIPDATA.
The log record was successfully delivered to CloudWatch.
Why wrong: That's OK.
The traffic was rejected by a network ACL or security group.
Why wrong: That shows in the action field.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
No network traffic was observed for the given capture period.
When VPC Flow Logs display 'NODATA' for the log-status field, it indicates that no network traffic was observed for the subnet during the aggregation interval (typically 10 minutes). This is a normal status meaning the capture window had zero packets flowing through the monitored interfaces, not an error or delivery issue.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
No network traffic was observed for the given capture period.
Why this is correct
Correct meaning.
Related concept
Read the scenario before looking for a memorised answer.
The flow log record was skipped due to an internal error.
Why it's wrong here
That's SKIPDATA.
The log record was successfully delivered to CloudWatch.
Why it's wrong here
That's OK.
The traffic was rejected by a network ACL or security group.
Why it's wrong here
That shows in the action field.
Common exam traps
AWS often tests the distinction between 'NODATA' (no traffic) and 'SKIPDATA' (internal error), leading candidates to incorrectly associate 'NODATA' with rejected traffic or delivery failures.
Trap categories for this question
Command / output trap
That shows in the action field.
Detailed technical explanation
VPC Flow Logs collect metadata about IP traffic at the network interface level, aggregating records into 10-minute windows by default. The 'NODATA' status specifically means the flow log publisher observed zero packets during that window, which can occur during idle periods or when the subnet has no active instances. This is distinct from 'SKIPDATA', which indicates the flow log service encountered an internal processing error and skipped the record.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.
What to study next
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FAQ
Network Design — This question tests Network Design — Read the scenario before looking for a memorised answer..
The correct answer is: No network traffic was observed for the given capture period. — When VPC Flow Logs display 'NODATA' for the log-status field, it indicates that no network traffic was observed for the subnet during the aggregation interval (typically 10 minutes). This is a normal status meaning the capture window had zero packets flowing through the monitored interfaces, not an error or delivery issue.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 2026
This ANS-C01 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 ANS-C01 exam.
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