Google PCA Manage implementation of cloud architecture Practice Question
A large e-commerce company runs a multi-tier application on Google Cloud. The frontend is served by a global HTTP Load Balancer with a backend service pointing to a managed instance group (MIG) of nginx web servers. The application tier consists of a regional internal TCP/UDP load balancer distributing traffic to a MIG of Java application servers. The database tier uses Cloud SQL for PostgreSQL in a failover replica configuration. The architecture is deployed in the us-central1 region across three zones. Recently, the operations team noticed intermittent 502 Bad Gateway errors from the frontend load balancer during peak traffic hours. The errors last for a few minutes and then recover. The team suspects the application tier is overwhelmed. They need to implement a solution that can handle traffic spikes without manual intervention. Which course of action should they take?
⚠ Common exam trap
Many exam-takers confuse frontend load balancer errors with frontend capacity issues and choose CDN or rate-limiting, but the 502 Bad Gateway error specifically indicates the backend (application tier) is failing to respond, so the solution must scale the application tier itself.
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
✓
Configure HTTP health checks on the regional internal load balancer and set the autoscaler to use the 'HTTP load balancing utilization' metric for the application tier MIG.
The intermittent 502 errors during peak traffic indicate that the application tier MIG is being overwhelmed. By configuring HTTP health checks on the regional internal load balancer and setting the autoscaler to use the 'HTTP load balancing utilization' metric, the autoscaler can scale the application tier MIG based on the actual load distribution from the internal load balancer, ensuring it handles traffic spikes without manual intervention. This directly addresses the root cause—insufficient application instances—by enabling dynamic scaling based on real-time utilization.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Increase the maximum number of instances in the application tier MIG from 10 to 20.
Why it's wrong here
Simply increasing max instances does not ensure that scaling happens quickly enough; autoscaling metrics must be tuned.
- ✗
Enable Cloud Armor on the frontend load balancer with a rate-limiting rule to block excessive traffic.
Why it's wrong here
Cloud Armor is for security, not for handling legitimate traffic spikes.
- ✓
Configure HTTP health checks on the regional internal load balancer and set the autoscaler to use the 'HTTP load balancing utilization' metric for the application tier MIG.
Why this is correct
Health checks ensure the load balancer only sends traffic to healthy instances, and autoscaling based on load balancing utilization will automatically adjust capacity.
- ✗
Enable Cloud CDN on the frontend load balancer to cache static assets and reduce load on the application tier.
Why it's wrong here
Cloud CDN caches static content, but the 502 errors likely come from dynamic requests that are not cacheable.
Go deeper
Related to this question
Learn chapter
Introduction to Google Cloud Platform
Key term
Autoscaler
An Autoscaler is a cloud service that automatically increases or decreases the number of virtual machines (instances) or resources based on real-time demand, so your application always has enough capacity without wasting money on idle servers.
Key term
TCP
TCP (Transmission Control Protocol) is a core internet protocol that ensures data is sent reliably and in order between devices over a network.
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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.