List of Azure Services that require a dedicated subnet

The following services can be deployed on a VNet but require a Subnet that cannot have any other Azure resource consiming the subnet private IPs. The minimum size for a Subnet in Azure is /29 whih provides 8 IP Addresses. However, Azure reserves some IP addresses within each subnet. The first and last IP addresses of each subnet are reserved for protocol conformance, along with the x.x.x.1-x.x.x.3 addresses of each subnet, which are used for Azure services.

Service	Subnet Size	Documentation
VPN and ExpressRoute Gateways	/27	https://docs.microsoft.com/en-us/azure/vpn-gateway/vpn-gateway-vpn-faq https://docs.microsoft.com/en-us/azure/expressroute/expressroute-howto-add-gateway-portal-resource-manager
App Gateway	/28	This size gives you 11 usable IP addresses. If your application load requires more than 10 IP addresses, consider a /27 or /26 subnet size. https://docs.microsoft.com/en-us/azure/application-gateway/configuration-overview#size-of-the-subnet
Azure Firewall	/26	https://docs.microsoft.com/en-us/azure/firewall/tutorial-firewall-deploy-portal
App Service Environment	/24	https://docs.microsoft.com/en-us/azure/app-service/environment/network-info
Redis Cache	/27	Each Redis instance in the subnet uses two IP addresses per shard and one additional IP address for the load balancer. A non-clustered cache is considered to have one shard. https://docs.microsoft.com/en-us/azure/azure-cache-for-redis/cache-how-to-premium-vnet
API Management	/27	https://docs.microsoft.com/en-us/azure/api-management/api-management-faq
SQL Server Managed Instance	/27	https://docs.microsoft.com/en-us/azure/sql-database/sql-database-managed-instance-connectivity-architecture#network-requirements
Integration Service Environment	/27	https://docs.microsoft.com/en-us/azure/logic-apps/connect-virtual-network-vnet-isolated-environment#create-subnet