Virtual Network Address Space

IP Address Classes

• Class A: 1.0.0.1 ~ 126.255.255.254 -> for large size network
• Class B: 128.1.0.1 ~ 191.255.255.254 -> for medium size network
• Class C: 192.0.1.1 ~ 223.255.254.254 -> for small size network
• Do not use class D and E

Normally I use: 10.8.0.0/16

• Sometime you Azure vNet might need to connect to on-premise network
• I used 2nd octate 8, because on-premise network might have address space 10.x.0.0/16 and there will be IP conflict if try to connect (Azure vNet <-> on-premise) via VPN

Subnets

• Consider how many types of resources will be provisioned
• Consider how many resources might need subnets
• Consider the max IP addresses might need for a subnet
  • If you are deploying cluster i.e. Kubernetes cluster, then you might need many IP addresses
  • If you are deploying VP Gateway, then few IP addresses will be suffucient

Normally I create following subnets (3rd octate is apart from each other by 20):

• AKSClusterSubnet: 10.8.0.0/21
• VMSubnet: 10.8.20.0/24
• AzureSQLSubnet: 10.8.40.0/24
• PrivateEndpointSubnet: 10.8.60.0/24 (i.e. for Azure Container Registry)
• Xyz: 10.8.80.0/24 …goes on
• GatewaySubnet: 10.8.255.0/27

Hub and Spoke Topology

• Hub:
  • common resources
  • connects onpremise via VPN or ExpressRoute
• Spokes:
  • protected resources
  • Multiple spokes are connected to hub using vNet peering
• Details: https://docs.microsoft.com/en-us/azure/architecture/reference-architectures/hybrid-networking/hub-spoke?tabs=cli