Google PCA Manage implementation of cloud architecture Practice Question
A company is designing a highly available architecture for a stateful application on Compute Engine. They need to protect against zonal failures. Which THREE steps should they take?
⚠ Common exam trap
A common misconception is that in-memory session state (Option A) is sufficient for high availability, but it fails because state is lost on instance failure; instead, external session stores (e.g., Cloud Memorystore or Cloud Spanner) are needed for stateful applications on Google Cloud.
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 a global load balancer with health checks
Option B is correct because a global external Application Load Balancer (or global external proxy Network Load Balancer) with health checks distributes traffic across healthy backends in multiple zones and automatically stops routing to unhealthy instances, providing resilience against a zonal failure. Option D is correct because regional persistent disks synchronously replicate data between two zones in the same region, so a stateful application's data remains available if one zone fails. Option E is correct because a managed instance group (MIG) spread across multiple zones maintains capacity and automatically recreates instances in surviving zones when a zone becomes unavailable. Option A is wrong because storing session state only in memory ties the state to a single instance and is lost on failure, breaking high availability. Option C is wrong because a single-zone instance group has no protection against a zonal outage.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Store session state in memory
Why it's wrong here
In-memory session state is tied to one VM's lifetime, so a zonal failure destroys it and users are logged out; state must be externalised to a shared store such as Memorystore or Cloud SQL. It is tempting because in-memory sessions are the fastest option for a single-instance, non-redundant deployment.
- ✓
Use a global load balancer with health checks
Why this is correct
A global external load balancer with health checks distributes traffic across healthy backends in multiple zones, automatically removing instances from a failed zone. This satisfies the zonal-failure requirement by redirecting users to surviving zones without manual intervention.
- ✗
Use a single zone instance group
Why it's wrong here
A single-zone instance group places every replica in one zone, so a zonal outage removes the entire capacity pool; a regional managed instance group spreads instances across zones. It is tempting because single-zone groups are adequate for dev, test, or workloads with no availability requirement.
- ✓
Use persistent disks with regional persistent disks
Why this is correct
Regional persistent disks synchronously replicate data across two zones, so a zonal outage leaves the application's state intact and mountable from the surviving zone. This directly addresses the stateful constraint that plain zonal persistent disks cannot satisfy.
- ✓
Use a managed instance group across multiple zones
Why this is correct
A managed instance group spread across multiple zones maintains capacity when one zone fails, satisfying the zonal-failure constraint. For a stateful application, however, this alone is insufficient: instance-level state is lost on recreation, so persistent disks or replicated storage must also be configured.
Go deeper
Related to this question
Learn chapter
Data Migration and Transfer Services
Key term
Zonal
Zonal refers to the practice of grouping computing resources within a single geographic area to improve fault isolation, reduce latency, and meet compliance requirements.
Key term
High availability
High availability is a system design approach that aims to keep applications and services operational and accessible with minimal downtime, even when some components fail.
About these practice questions
One of 807 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 by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This PCA 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 PCA exam.