Quota and IP exhaustion look alike until you inspect the failed resource

Both failures can leave Pods Pending while the autoscaler tries to add capacity. The decisive evidence is the failed node or address allocation event.

Signal	Quota or stock	IP exhaustion
Provider event	Resource quota exceeded or requested machine unavailable	Subnet or Pod secondary range exhausted
Check	Regional CPU, accelerator and address quotas; zone capacity	Primary node range, Pod secondary ranges and max Pods per node
Fix	Raise quota, change fallback shape or zone	Expand supported ranges, add discontiguous Pod CIDR or redesign density
Prevention	Forecast peaks and preflight quota	Size from maximum nodes with growth headroom

Compute, quota and IP space are three separate capacity budgets.

Quota and IP exhaustion is easiest to understand by separating the Kubernetes contract from the Google Cloud implementation. GKE infrastructure scaling depends on Google Cloud quota, regional stock and available subnet address space. A failure in any one prevents a new node from becoming usable. The Kubernetes objects stay familiar, but GKE supplies controllers, infrastructure and safe defaults around them. This is why a team can move from an on-premises cluster without rewriting every workload, while still needing to redesign networking, identity and operational ownership for the cloud environment.

A useful inspection step is `gcloud compute regions describe europe-west1`. Read the output as evidence, not as a ritual: first confirm the desired object exists, then look at status conditions, events and the Google Cloud resource it represents. In production, capture the expected result in a runbook or automated check so an operator can distinguish slow reconciliation from a configuration error.

Production gotcha: A larger Pod CIDR does not help if the subnet primary node range is exhausted, and vice versa. The safe habit is to verify quotas, regional availability and feature support against current Google Cloud documentation before rollout. Admission webhooks create a different control-plane failure shape.