PCA Observability Concepts Practice Question
An engineer observes a massive spike in Prometheus memory usage after introducing a new custom label that includes a unique user ID. Which observability concept is being violated?
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
✓
High cardinality
High cardinality occurs when a metric label has an unbounded number of unique values, which causes Prometheus to create a unique time series for every combination, leading to memory exhaustion.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Data retention policy
Why it's wrong here
Retention policies manage disk space, not memory pressure from active series.
- ✗
Metric saturation
Why it's wrong here
Saturation refers to the degree of consumption of a resource, not memory usage by labels.
- ✗
Service discovery limits
Why it's wrong here
Service discovery manages targets, not the number of label combinations.
- ✓
High cardinality
Why this is correct
Including highly unique values like user IDs in labels creates excessive time series, causing high memory usage.
About these practice questions
One of 304 original PCA practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed August 2026 · checked against the official CNCF / Linux Foundation exam blueprint
This PCA practice question is part of Courseiva's free CNCF / Linux Foundation 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 PCA exam.