Understanding the distinction between Azure Private Link and Private Endpoint is essential for architects designing secure cloud connectivity. These terms are frequently used interchangeably, yet they represent different components of the same secure access model. The confusion often arises because one is the foundational service and the other is the tangible interface that consumes that service. This breakdown creates a secure connection between your on-premises environment and Azure services over the Microsoft Azure backbone.
Defining the Core Concepts
At the architectural level, Azure Private Link is the technology that enables the creation of a private endpoint for a PaaS service. It is the mechanism that provisions a private IP address within your Virtual Network (VNet) and securely connects it to the Azure service via a zonal or regional endpoint. Without Private Link, the service remains exposed to the public internet. Private Endpoint, conversely, is the network interface that sits within your VNet, acting as the entry point for traffic destined for the linked service.
The Mechanics of Connectivity
Traffic flows from your on-premises network through a Site-to-Site VPN or ExpressRoute circuit into your VNet. When you configure a Private Endpoint for a service such as Azure Storage or Azure SQL, a network interface is created in your subnet. This interface receives a private IP address from the subnet’s address space. All communication between your resources and the Azure service is routed directly over this private interface, bypassing the public internet entirely.
Security and Network Isolation
The primary driver for implementing these technologies is security. By utilizing Private Link, you eliminate the exposure of public IP addresses associated with the service. This significantly reduces the attack surface, as the service is no longer accessible via the public internet. Access is restricted to the Virtual Network where the Private Endpoint is deployed, enforcing strict network isolation and compliance requirements.
DNS Resolution and Routing
For the connection to function seamlessly, DNS resolution must be configured correctly. When a Private Endpoint is created, Azure automatically registers the private IP address against the FQDN of the service within the VNet. This ensures that when a resource inside the VNet attempts to connect to the service name, it is directed to the private IP rather than the public one. Without this internal DNS mapping, traffic would fail to route to the private interface.
Architectural Comparison and Use Cases
While the terms are linked, comparing them clarifies their roles in the infrastructure. The following table outlines the primary characteristics and responsibilities of each component.
