DA0-002 Data Concepts and Environments Practice Question
A data engineer is profiling a dataset of online orders. The order_id column contains a unique value for every row, but the analyst notices that a join to the customer table unexpectedly returns fewer rows than the orders table. After investigation, the engineer finds that some customer_id values in the orders table do not exist in the customer table. Which data quality dimension is primarily violated by the customer_id values?
⚠ Common exam trap
The trap here is treating orphaned foreign keys as a completeness problem because rows disappear, when the underlying defect is a broken relationship between tables.
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
✓
Referential integrity
When foreign key values in the orders table fail to match primary keys in the customer table, the relationship between the tables is broken, which is a referential integrity violation. That is why the join loses rows. Accuracy, completeness, and timeliness describe other properties of data and do not capture a missing parent record for a valid-looking child key.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Referential integrity
Why this is correct
Referential integrity requires that a foreign key value in one table matches a primary key value in the referenced table. The customer_id values that have no matching customer row violate that rule, which is why the join drops rows. This is the precise dimension describing broken relationships between related tables, distinct from general accuracy or completeness of a single column.
- ✗
Timeliness
Why it's wrong here
Timeliness measures whether data is available and current enough for its intended use, such as whether yesterday's orders have loaded. The orphaned customer_id values are not a latency problem; they would remain invalid regardless of when the data arrived. Applying timeliness here would direct remediation toward refresh schedules instead of fixing the broken key relationships.
- ✗
Accuracy
Why it's wrong here
Accuracy measures whether a value correctly reflects the real-world object it describes, such as whether a customer's address is truly correct. Here the issue is not that customer_id is a wrong identifier for the real customer, but that it points to a customer record that does not exist in the referenced table. The failure is relational, not a mismatch with reality.
- ✗
Completeness
Why it's wrong here
Completeness concerns whether expected values are present, such as whether every order has a non-null customer_id. In this scenario the customer_id values are populated; they simply do not resolve to existing customer records. Treating this as completeness would misdiagnose the problem and lead to checking for nulls rather than validating cross-table relationships.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official CompTIA exam blueprint
This DA0-002 practice question is part of Courseiva's free CompTIA 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 DA0-002 exam.