VNet service endpoints are an extension of a virtual network private address space and a VNet to connect to Azure PaaS services through a direct connection through the Azure backbone to those services. Those private connections and endpoints allow services, virtual machines or users to secure critical and access Azure PaaS service resources only from a virtual network. Traffic from a VNet to the Azure service remains on the Microsoft Azure backbone network at any time, even if the communication between the endpoint and VNet is established through public IPs.

Currently VNet endpoints are GA for following services: 

• Azure Storage: Generally available in all Azure regions
• Azure SQL Database: Generally available in all Azure regions
• Azure Database for PostgreSQL server: Generally available in Azure regions where database service is available
• Azure Database for MySQL server: Generally available in Azure regions where database service is available
• Azure Cosmos DB: Generally available in all Azure public cloud regions
• Azure Key Vault: Generally available in all Azure public cloud regions

Following services are currently in preview: 

• Azure SQL Data Warehouse: Available in preview in all Azure public cloud regions
• Azure Service Bus: Available in preview
• Azure Event Hubs: Available in preview
• Azure Data Lake Store Gen 1: Available in preview