PDE Storing the Data Practice Question
A company is using BigQuery for analytics and needs to ensure that certain columns containing PII are encrypted with a customer-managed key (CMEK). Which approach should they take?
⚠ Common exam trap
Google often tests the distinction between dataset-level encryption (CMEK at the dataset or table level) and column-level encryption; the trap here is that candidates assume CMEK applies only at the dataset level, missing that BigQuery supports field-level encryption via AEAD functions with Cloud KMS keys for granular control.
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
✓
Use BigQuery column-level encryption with AEAD functions and a Cloud KMS key.
BigQuery column-level encryption using AEAD (Authenticated Encryption with Associated Data) functions allows you to encrypt specific columns containing PII with a customer-managed key (CMEK) stored in Cloud KMS. This approach provides granular, field-level encryption that meets compliance requirements without affecting the rest of the table or dataset, and the encryption/decryption is performed transparently within BigQuery using the AEAD.DECRYPT_STRING function.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Use Cloud Data Loss Prevention (DLP) to mask the columns during query.
Why it's wrong here
DLP can mask data but does not encrypt at rest with CMEK.
- ✓
Use BigQuery column-level encryption with AEAD functions and a Cloud KMS key.
Why this is correct
Correct: AEAD functions enable column-level encryption with CMEK.
- ✗
Apply CMEK at the dataset level; all tables inherit the encryption.
Why it's wrong here
Dataset-level CMEK encrypts all data at rest but does not allow per-column control.
- ✗
Store the data encrypted in Cloud Storage and use external tables with a CMEK.
Why it's wrong here
External tables can use CMEK for storage, but not for column-level encryption within BigQuery.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This PDE practice question is part of Courseiva's free Google Cloud 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 PDE exam.