Regions, Zones and the Global Network

GCP Basics · Foundations – Regions, Resource Hierarchy, gcloud and Billing · Lesson 1 of 5

A region is a geographic area with three or more zones; zonal, regional and global resources fail in different ways, and Google’s private backbone connects them all.

Google Cloud runs in regions (for example asia-southeast1 in Singapore) and every region has three or more zones (asia-southeast1-a, -b, -c). A zone is an isolated failure domain inside the region. All regions are joined by Google’s private fibre backbone, which is why some resources can be global.

flowchart LR
  U["Users in Vietnam"] --> E["Edge PoP / Cloud CDN"]
  E --> G["Google backbone (global)"]
  G --> R1["Region asia-southeast1"]
  R1 --> Z1["Zone asia-southeast1-a"]
  R1 --> Z2["Zone asia-southeast1-b"]
  G --> R2["Region asia-southeast2"]
  %% step U: A request from a user enters Google’s network at the nearest edge point of presence.
  %% step E: Edge PoPs host Cloud CDN and the global load balancer front ends close to users.
  %% step G: From the edge, traffic rides Google’s private backbone instead of the public Internet.
  %% step R1: A region such as asia-southeast1 groups three or more zones with low-latency links between them.
  %% step Z1: A zone is one failure domain; a zonal VM or disk lives in exactly one zone.
  %% step R2: A second region gives you protection against a whole-region outage.

Three scopes of resources

Scope	Examples	Survives the loss of
Zonal	Compute Engine VM, zonal Persistent Disk, zonal GKE cluster	nothing outside the zone
Regional	Regional MIG, regional Persistent Disk, Cloud SQL HA, subnet, Cloud Run service	one zone
Global	VPC network, firewall rules, global external Application Load Balancer, images, snapshots (multi-regional)	one region

A VPC network is global: one network can hold subnets in many regions, and VMs in different regions talk over internal IPs without VPNs. Subnets are regional. This is the biggest difference from AWS and Azure, where a VPC/VNet belongs to one region.

Choosing a region

Latency to your users. For Vietnam, asia-southeast1 (Singapore) and asia-southeast2 (Jakarta) are the closest.
Data residency and compliance rules.
Service availability: not every product or machine type exists in every region; check the product’s locations page.
Price: the same VM can cost more in one region than another.
Carbon: Google publishes a carbon-free energy percentage per region.

Designing for failure

Run at least two instances in two zones (a regional managed instance group) to survive a zone failure.
Use regional services (Cloud SQL HA, regional Persistent Disk) for stateful data.
Use a second region plus a global load balancer for disaster recovery.

Network Service Tiers

Premium tier (default) carries traffic on Google’s backbone as far as possible and is required for global load balancing. Standard tier hands traffic to the public Internet near the region: cheaper, but regional only.

Command	Meaning
`gcloud compute regions list`	All regions and their quotas
`gcloud compute zones list --filter="region:asia-southeast1"`	Zones in one region
`gcloud config set compute/region asia-southeast1`	Default region for commands

Traps: a zone name is the region plus a letter, but zone letters are not the same physical buildings for every customer; and “multi-region” in Cloud Storage (ASIA) is not the same as running your app in many regions.