Google Cloud VMs and Networking

In Google Cloud, every Virtual Machine (VM) must be connected to a Virtual Private Cloud (VPC) network. If there’s no VPC, you can’t launch a VM.

Basics

1. VPC - A global, isolated virtual network within your GCP project. It spans all regions.
2. Subnets are regional; each region must have its own subnet to launch resources like VMs
3. VMs are always launched inside a subnet, which belongs to a VPC.

Even though subnets are regional, a VPC itself is global. That means VMs in different regions (but within the same VPC) can communicate with each other internally, without needing external IP addresses or a VPN.

Firewall Rules

1. Firewall rules in GCP apply at the network level, not the individual VM.
2. Default behaviour: all incoming traffic is denied by default.
3. You must explicitly allow traffic

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