Networking is central to administering Azure, requiring understanding of public and private IP addresses and IPv4 address spaces.
Azure networking uses familiar TCP/IP principles, but implements them through software-defined virtual networking rather than physical cables and network cards.
VNets and subnets
A virtual network, or VNet, is the base networking unit in Azure and is assigned an address space such as 10.2.0.0/16.
A VNet can contain one or more subnets, each using part or all of the VNet address space, such as 10.2.1.0/24, 10.2.2.0/24, and 10.2.3.0/24.
Subnets can represent application tiers such as frontend, business tier, and backend in a three-tier architecture.
Reserved addresses
In each subnet, TCP/IP reserves the first and last address, and Azure reserves the first three available addresses for the default gateway and DNS services.
For a /24 subnet with 256 total addresses, only 251 are usable because five addresses are unavailable.
The first usable VM address in a 10.2.1.0/24 subnet is 10.2.1.4.
Routing and communication
By default, all subnets inside the same VNet can communicate with each other through system-defined routes.
Azure automatically creates the default routing behavior when a VNet is built, so basic subnet communication does not require manually building route tables.
External access requires a gateway or public IP address assigned to the appropriate resource.
Address planning
Private IPv4 ranges available for Azure private networking include 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16.
Address spaces that communicate directly must not overlap, even though Azure may allow creation and only display a warning.
Use appropriately sized address ranges to avoid wasting IP space and limiting future growth.
Do not manage IP addresses inside the VM operating system; manage them through Azure software-defined networking settings.
Public IP addresses
Public IP addresses are allocated from Azure regional pools and can be dynamic or static.
Static public IP addresses remain allocated to you and incur cost while reserved, whether or not they are actively used.
Azure can support bringing your own public IP addresses if you provide proof of ownership for the required public address block.
Public IP addresses should generally be limited to ingress and egress points such as firewalls, gateways, and application gateways.
Portal demonstration
The demo creates a virtual network resource in the Azure portal, selects a subscription, resource group, VNet name, and region.
VNets are regional resources and cannot span regions, though they can communicate with other VNets and networks.
The demo configures a /16 VNet address space and creates /24 subnets named frontend, business tier, and backend.
After creation, Azure shows subnet availability, overlap warnings, connected devices, and available address counts such as 251 per /24 subnet.
Module recap
Azure virtual networking uses the same TCP/IP fundamentals as on-premises networking, with Azure-specific terminology and reserved address behavior.
A VNet defines an address space using CIDR notation, and that space is divided into one or more subnets.
Actiepunten
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