What is the minimum subnet size that provides usable IP addresses in Google Cloud?

The minimum subnet size that provides usable IP addresses in Google Cloud is a /29 subnet.

A /29 subnet mask allows for 8 total IP addresses (2^3 = 8). However, two of these IP addresses are reserved: one for the network address and one for the broadcast address. This leaves 6 usable IP addresses for hosts within that subnet. In scenarios where you need to allocate resources such as virtual machine instances, a /29 subnet is suitable as it provides enough IP addresses for small-scale deployments while adhering to Google's requirement for subnet sizes.

Using larger subnet sizes, like /28 or /27, would provide more IP addresses than necessary if only a few are required, while a /30 subnet would only provide 2 usable IP addresses, which is insufficient for most application needs. Thus, a /29 is the smallest subnet that effectively provides a reasonable number of usable addresses while maintaining the structure and flexibility for resource distribution in a Google Cloud environment.