mediumMultiple ChoiceObjective-mapped
Google ACE Practice Question: Your application runs on Compute Engine instances…
Your application runs on Compute Engine instances behind a regional external HTTP(S) load balancer. Users report intermittent timeouts during periods of high traffic. Health checks show all instances as healthy. Which two configuration parameters should you review first?
⚠ Common exam trap
Google Cloud often tests the misconception that health check status alone guarantees application availability, but candidates must understand that load balancer configuration parameters like connection draining and session affinity can cause timeouts even when all instances are healthy.
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
✓
Review connection draining and session affinity settings
B is correct because connection draining (drain mode) and session affinity settings directly affect how the load balancer handles in-flight requests and distributes traffic during high load. Connection draining ensures existing connections complete before an instance is removed, preventing abrupt timeouts. Session affinity (sticky sessions) can cause uneven traffic distribution if misconfigured, leading to overloaded instances and intermittent timeouts even when health checks pass.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Check SSL certificate expiration
Why it's wrong here
An expired SSL certificate is a discrete, deterministic event: once the certificate is invalid, every TLS handshake through the load balancer fails consistently until it is renewed. Intermittent timeouts that appear only under load, and that affect some requests while others succeed, are not explained by certificate expiration. Checking certificate expiry is still a valid hygiene step, but it does not match the described failure signature.
- ✓
Review connection draining and session affinity settings
Why this is correct
Connection draining determines how long in-flight requests are allowed to finish on an instance being removed, for example during autoscaling scale-in or a rolling update; if that timeout is set too low, requests are cut off exactly during load spikes when instances are cycled. Session affinity (sticky sessions) can compound this by pinning a client to one backend instance; if that instance becomes overloaded or is drained while its neighbors are healthy, that client's requests will intermittently hang or time out. Reviewing these load-balancer backend settings directly addresses the pattern of intermittent timeouts under load.
- ✗
Increase instance machine type (size)
Why it's wrong here
Increasing the machine type adds CPU and memory capacity, but the symptom is not necessarily driven by sustained resource exhaustion — timeouts that come and go with load can be caused by connection lifecycle management, not by hitting a compute ceiling. A larger instance will still have its in-flight connections terminated by the same aggressive draining or affinity behavior, and if the real bottleneck is, for example, backend connection queue limits, the larger machine may not even change the timeout profile. Right-sizing should follow metric analysis, not be used as a blanket fix.
- ✗
Enable Cloud CDN
Why it's wrong here
Cloud CDN caches static objects at Google's edge and can reduce origin load, but it does not modify how the load balancer manages TCP connections to backend instances, nor does it affect connection draining or session affinity. For dynamic, session-bound, or uncacheable requests, CDN will simply forward the request to the origin, so the intermittent timeout behavior remains unchanged. In fact, enabling CDN without careful path configuration can make debugging harder by introducing cached 404s or stale content.
Go deeper
Related to this question
Learn chapter
Google Compute Engine
Key term
HTTP(S) Load Balancer
A network device or software that distributes incoming web traffic across multiple servers using HTTP or HTTPS protocols to ensure high availability, reliability, and performance.
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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JA
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.