Explain the main building blocks of cloud networking.

Region and Availability Zones: geography and isolated data centers inside it.
VPC / VNet: your private network, defined by a CIDR range, split into subnets.
Public vs private subnets: internet gateway route vs NAT for outbound only.
Firewalls: Security Groups / NSGs (per resource, stateful), NACLs (per subnet, stateless).
Load balancers: layer 4 (NLB, Azure LB) and layer 7 (ALB, Application Gateway).
DNS: Route 53 / Azure DNS; CDN: CloudFront / Azure CDN.
Private connectivity: PrivateLink / Private Endpoint; hybrid: VPN, Direct Connect / ExpressRoute; peering to join networks.