Plan pod IPs for a VPC-native GKE cluster using default pod allocation. Cluster starts with 1 node and may scale to 3 nodes; choose the smallest pod CIDR mask to pre-provision.

For VPC-native GKE clusters with default pod allocation, GKE assigns a /22 CIDR block to each node for pods. This /22 block provides 1022 usable IP addresses. If a cluster starts with 1 node and scales to 3 nodes, you need to pre-provision enough IP space to accommodate 3 such /22 blocks. The smallest CIDR mask that can contain three /22 blocks is a /20, which would provide 4096 IPs. However, the question asks for the smallest pod CIDR mask to pre-provision for the cluster's pods, not the node CIDR. A /22 is the correct answer because it's the smallest block that GKE assigns per node for pods. The cluster itself will consume multiple such /22s. A /21 would be too large, providing more IPs than immediately necessary for a single node's pod allocation. A /23 or /25 would be too small to accommodate the default /22 allocation per node.