Azure Learning

vnet

Properties2
tagsnetworking, vnet, azure-core
aliasesVNet, virtual-network

2 min read

Virtual Network (VNet)

What it is

An Azure Virtual Network (VNet) is Azure’s software-defined networking fabric — an isolated, customer-controlled private network in the cloud. It is the top-level container that hosts your subnets, NICs, and the majority of Azure networking services (VMs, load balancers, firewalls, DNS).

Why it exists

Physical networks were constrained by hardware and on-premises cabling. A VNet gives you the same segmentation, routing, name resolution, and security primitives as an on-prem LAN, but delivered as an isolated slice of Azure’s shared cloud — provisioned in seconds and fully API-managed.

Key ideas

  • Bound to a region and a subscription (a VNet can span multiple availability zones in its region, but not regions).
  • Defined by a private IP address space (e.g. 10.0.0.0/16) using CIDR; it does not create routes to the internet by default — a public IP + route is needed.
  • Split into one or more subnet.
  • Traffic to the internet, to on-premises, and between VNets is governed by routes and network security groups.
  • VNets are linked to each other via vnet-peering and to on-premises via vpn-gateway or expressroute.

How it fits

vnet.svg

Internet │  On-premises
   │      │      │
   ▼      ▼      ▼
[ public IP ][ VPN Gateway / ER ]
   ┌────────────── VNet (10.0.0.0/16) ──────────────┐
   │  Subnet A (10.0.1.0/24)    Subnet B (10.0.2.0/24) │
   │  [VM][LB]                   [VM][ASG]            │
   │  NSG / route tables / Azure Firewall             │
   └───────────────────────────────▲──────────────────┘
                                   │ vnet-peering
                          ┌────────┴────────┐
                          │  other VNet     │
                          └─────────────────┘

Exam notes

  • VNet is regional; a VNet cannot span regions. Create one VNet per region per tier to isolate at region granularity.
  • A VNet without a default outbound route can’t reach the internet — note the modern default-outbound-access changes; rely on explicit public IP/NAT unless using default outbound.
  • VNets are free; you pay for the resources inside (gateways, public IPs, etc.), and peering data transfer.
  • Deleting a VNet requires all dependent resources (subnets, NICs, peering links) to be removed first.

Home · subnet · cidr-ip-addressing · vnet-peering · route-table · nsg · azure-dns

📘 Source: Microsoft Learn — Vnet

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