KCNA Cloud Native Architecture Practice Question

In a serverless architecture using Knative, what happens to a service that has not received traffic for an extended period?

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

✓

It scales down to zero replicas and is reactivated on the next request

Knative scales to zero when idle, meaning no pods are running, thus no cost incurred.

Answer analysis

For each option: why learners choose it and why it is or isn't the right answer here.

✗
It throws an error and must be redeployed
Why it's wrong here
Knative scales idle services to zero replicas rather than erroring; the Deployment and Route remain defined and traffic resumes automatically. Erroring and redeployment describes a crashed workload, not scale-to-zero behaviour, so this misreads the autoscaling mechanism that Knative's activator and queue-proxy implement.
✗
It continues running with one replica to reduce cold start latency
Why it's wrong here
Knative's default scale-to-zero removes all replicas when idle, so no pod persists to warm caches. Keeping one replica running describes a minimum-scale setting used to avoid cold starts in latency-sensitive workloads, not the default outcome after extended inactivity.
✓
It scales down to zero replicas and is reactivated on the next request
Why this is correct
Knative's autoscaler, via the Activator and queue-proxy, reduces idle services to zero replicas after the configured scale-to-zero window, eliminating compute cost. The next incoming request is buffered by the Activator, which spins up a pod and forwards traffic.
✗
It is automatically deleted
Why it's wrong here
Scale-to-zero removes running pods but preserves the Knative Service, Configuration and Route objects, so the service is not deleted and reactivates on request. Automatic deletion describes cleanup of orphaned resources, not the idle behaviour of a defined Knative service.

Quick reference

Model	You Manage	Provider Manages	Examples
IaaS	OS, runtime, apps, data	Hardware, hypervisor, networking	EC2, Azure VMs, GCP Compute Engine
PaaS	Apps and data	OS, runtime, middleware, hardware	Elastic Beanstalk, Azure App Service
SaaS	Data and settings only	Everything else	Microsoft 365, Salesforce, Workday
FaaS / Serverless	Function code only	Infra, scaling, runtime	Lambda, Azure Functions, Cloud Run
CaaS	Containers and apps	Kubernetes, OS, hardware	EKS, AKS, GKE

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