{ "properties": { "displayName": "Allow only 10.4.X.X vNet creation", "policyType": "Custom", "mode": "All", "metadata": { "category": "Network" }, "parameters": {}, "policyRule": { "if": { "allOf": [ { "field": "type", "equals": "Microsoft.Network/virtualNetworks" }, { "field": "Microsoft.Network/virtualNetworks/addressSpace.addressPrefixes[*]", "notContains": "10.4." } ] }, "then": { "effect": "deny" } } } }