Azure Virtual Network

As soon as cloud resources multiply, teams need to know who can reach what. Without network boundaries, environments blur together, databases are exposed too broadly, and firewall rules become hard to reason about because the underlying placement lacks structure.

Early cloud adoption often began with provider-managed networking defaults. That worked until teams needed environment separation, hybrid connectivity, and tighter traffic boundaries. Software-defined private networking became the cloud answer to the physical routers, switches, and segmentation patterns teams used before.

A virtual network starts with an address range, then divides that range into subnets for different traffic roles. Security groups apply protocol and port rules, gateways define north-south traffic paths (traffic entering or leaving the network boundary, as opposed to east-west traffic between internal resources), and peering or private links connect additional private paths. Together these decisions turn a flat cloud space into an intentional traffic topology.

Azure Virtual Network and AWS VPC solve nearly the same problem: define a private cloud network, split it into subnets, apply security controls, and route traffic intentionally. The design choices diverge in specific ways that affect how teams plan. VNet peering works across regions natively, while VPC peering is regional by default and cross-region peering carries different latency and cost trade-offs. Security groups in Azure attach to subnets or individual NICs and are stateful at the NIC level, whereas VPC security groups attach to instances and are paired with separate subnet-level network ACLs. If your design relies on cross-region private connectivity, VNet's global peering model is simpler to set up. If you prefer separating subnet-level and instance-level rules into distinct policy layers, VPC's split between security groups and NACLs gives that explicitly.

A virtual network is the starting point for placing application tiers into controlled private address space. Teams usually begin by carving public-facing and internal-only subnets, then extend the design with environment separation, peering, or private connectivity to platform services. The design matters early because address overlap becomes painful once environments and connections start to multiply.