What is the hard limit for the number of primary IP ranges per subnet?

The hard limit for the number of primary IP ranges per subnet in Google Cloud is indeed one. Each subnet in a Virtual Private Cloud (VPC) can only have a single primary IP range allocated to it. This restriction simplifies the management of IP addressing within subnets and ensures that there is a clear and unambiguous allocation of IP addresses within the network.

When a subnet is created, a primary IP range is designated, which defines the IP address space from which instances within that subnet can be assigned addresses. The decision to limit this to one primary range is primarily to avoid complications associated with overlapping IP ranges, which could lead to routing issues and conflicts in network operations.

Secondary IP ranges can be added to a subnet, allowing for more complex scenarios such as aliasing IP addresses for services like Kubernetes clusters, but they are not considered primary IP ranges. This distinction highlights the simplicity of the primary IP range concept, which is essential for maintaining clear network structure and integrity in Google Cloud environments.