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Google ACE Practice Question: A small business is deploying a web application…
A small business is deploying a web application on Compute Engine and wants to ensure high availability. They have set up two instances in different zones behind a TCP load balancer. What should they also configure to detect and route traffic away from unhealthy instances?
⚠ Common exam trap
Candidates often confuse health checks with firewall rules or backup strategies, thinking that allowing traffic or creating snapshots ensures availability, but only health checks provide the active monitoring needed to detect and route around failures.
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 a health check on the load balancer.
A health check is required for the TCP load balancer to monitor the backend instances. It periodically probes the instances on a specified port and path, marking them as unhealthy if they fail to respond. The load balancer then stops routing new traffic to unhealthy instances, ensuring high availability by directing traffic only to healthy backends.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Configure a health check on the load balancer.
Why this is correct
Configuring a health check on the load balancer enables scheduled probes to be sent to each backend instance on a designated port and path. If an instance fails to respond with the expected status code or TCP handshake after multiple attempts, it is automatically removed from the load balancer's backend pool. This stops new traffic from being routed to a failed or overloaded instance, which is exactly the detection required in this scenario.
- ✗
Set a firewall rule to allow traffic only on port 80.
Why it's wrong here
A firewall rule that allows traffic only on port 80 controls which network packets can reach the instance, but it provides no mechanism for determining whether the web application is actually running or responding correctly. In fact, such a rule could block the load balancer's health check probes if those probes are configured to use a different port or protocol. Firewall rules can support health monitoring, but they are not a substitute for configuring a health check and do not themselves detect unhealthy instances.
- ✗
Use a global HTTP(S) load balancer instead.
Why it's wrong here
Switching to a global HTTP(S) load balancer would not solve the problem because this load balancer also requires health checks to be configured on the backend service before it can detect unhealthy instances. Additionally, the global HTTP(S) load balancer operates at Layer 7 and is only appropriate for HTTP and HTTPS traffic, not for arbitrary TCP/UDP workloads that a network load balancer handles. Therefore, this option does not provide a health-detection mechanism and is the wrong substitute for configuring a health check.
- ✗
Create a snapshot schedule for the persistent disks.
Why it's wrong here
Creating a snapshot schedule for persistent disks simply automates backup of disk data to Cloud Storage for disaster recovery purposes. Snapshots capture the disk state at a point in time, but they do not monitor the status of the application or instance in real time. As a result, a snapshot schedule has no effect on load balancer traffic routing and cannot remove a failed instance from the load-balanced pool, so it is irrelevant to health detection.
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Google Compute Engine
Key term
Route
A route is a path that data takes through a network from one device or network to another, determined by routing protocols and configured rules.
Key term
Compute Engine
Compute Engine is Google Cloud's Infrastructure-as-a-Service (IaaS) offering that lets you create and run virtual machines on Google's infrastructure.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This ACE 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 ACE exam.