- A
Round-robin distribution — traffic cycles evenly across all instances regardless of health.
Why wrong: Round-robin distributes traffic evenly but doesn't account for instance health. Without health checks, round-robin continues sending requests to failed instances.
- B
Health checks — the load balancer probes backend instances and removes unhealthy ones from the serving pool.
Health checks detect failed backends by sending periodic probe requests. Unhealthy backends are removed from rotation; remaining healthy instances absorb the traffic. This is automatic fault detection.
- C
SSL termination — decrypting HTTPS traffic before forwarding to backends.
Why wrong: SSL termination decrypts encrypted traffic at the load balancer, not a health or availability feature. It handles encryption, not fault detection.
- D
Session affinity — routing the same user to the same backend instance.
Why wrong: Session affinity (sticky sessions) routes a user consistently to the same backend for stateful applications. It doesn't automatically remove failed backends from rotation.
Quick Answer
The answer is health checks, as they are the load balancing feature that enables automatic failover by probing backend instances and removing unhealthy ones from the serving pool. When a health check fails—due to a timeout, connection refusal, or non-2xx response—the load balancer instantly stops routing traffic to that instance, rerouting requests to the remaining healthy copies. On the Google Cloud Digital Leader exam, this concept tests your understanding of how Google Cloud’s external and internal load balancers maintain high availability without manual intervention; a common trap is confusing health checks with autoscaling, which adds instances rather than removing failed ones. Remember the mnemonic “Probe to Remove”: health checks probe the backend, and a failed probe triggers removal, ensuring seamless failover and fault tolerance for global applications.
Cloud Digital Leader Fundamental cloud concepts Practice Question
This GCDL practice question tests your understanding of fundamental cloud concepts. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company hosts a web application that receives requests from users globally. To handle failures, they run three identical copies of their application behind a load balancer. When one copy fails, the load balancer automatically stops sending traffic to it. What load balancing feature enables this?
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
Health checks — the load balancer probes backend instances and removes unhealthy ones from the serving pool.
Health checks are the load balancing feature that proactively monitors the status of backend instances by sending periodic probes (e.g., HTTP GET requests, TCP SYN packets) to a configured endpoint. If a health check fails (e.g., non-2xx response, timeout, or connection refused), the load balancer automatically marks that instance as unhealthy and stops routing new traffic to it, ensuring high availability and fault tolerance.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Round-robin distribution — traffic cycles evenly across all instances regardless of health.
Why it's wrong here
Round-robin distributes traffic evenly but doesn't account for instance health. Without health checks, round-robin continues sending requests to failed instances.
- ✓
Health checks — the load balancer probes backend instances and removes unhealthy ones from the serving pool.
Why this is correct
Health checks detect failed backends by sending periodic probe requests. Unhealthy backends are removed from rotation; remaining healthy instances absorb the traffic. This is automatic fault detection.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
SSL termination — decrypting HTTPS traffic before forwarding to backends.
Why it's wrong here
SSL termination decrypts encrypted traffic at the load balancer, not a health or availability feature. It handles encryption, not fault detection.
- ✗
Session affinity — routing the same user to the same backend instance.
Why it's wrong here
Session affinity (sticky sessions) routes a user consistently to the same backend for stateful applications. It doesn't automatically remove failed backends from rotation.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between traffic distribution algorithms (like round-robin) and health monitoring features, leading candidates to mistakenly believe that round-robin inherently handles failures because it 'spreads traffic evenly,' when in fact it has no awareness of instance health.
Detailed technical explanation
How to think about this question
Under the hood, health checks are configured with parameters such as the probe interval (e.g., every 5 seconds), timeout (e.g., 2 seconds), unhealthy threshold (e.g., 3 consecutive failures), and healthy threshold (e.g., 2 consecutive successes). The load balancer maintains a state table for each backend instance, and when the unhealthy threshold is crossed, the instance is removed from the active rotation; traffic is only resumed after the healthy threshold is met again. In a real-world scenario, if a backend instance experiences a memory leak that causes it to respond slowly but not crash, health checks with a short timeout can detect the degradation and remove it before users experience timeouts.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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FAQ
Questions learners often ask
What does this GCDL question test?
Fundamental cloud concepts — This question tests Fundamental cloud concepts — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Health checks — the load balancer probes backend instances and removes unhealthy ones from the serving pool. — Health checks are the load balancing feature that proactively monitors the status of backend instances by sending periodic probes (e.g., HTTP GET requests, TCP SYN packets) to a configured endpoint. If a health check fails (e.g., non-2xx response, timeout, or connection refused), the load balancer automatically marks that instance as unhealthy and stops routing new traffic to it, ensuring high availability and fault tolerance.
What should I do if I get this GCDL question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
This GCDL 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 GCDL exam.
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