Azure Private Endpoints: How They Actually Work (And When You Should Use Them)

I often hear about how engineers don’t want to use private endpoints. What it really comes down to is, they don’t understand how they work. Let’s dive in and see what all the magic is about.

One of the things that surprises engineers when they start building real platforms in Azure is how many core services are public by default.

Create a storage account.
Create a Key Vault.
Create an Azure SQL database.

Each one immediately gets a DNS endpoint like this:

mystorage.blob.core.windows.net
myvault.vault.azure.net
mydb.database.windows.net

That endpoint lives on the public internet.

Yes, you can restrict access with firewall rules.
Yes, authentication is still required.

But the service itself is still publicly reachable.

For small environments, that’s usually fine. Most teams never think twice about it.

You may be comfortable initially. However, once you start working on larger platforms, things change. This is especially true in enterprise or regulated environments. That design starts raising uncomfortable questions.

Security teams ask things like:

“Why does our production database have a public endpoint at all?”

That’s usually the moment where someone suggests using Azure Private Endpoints.

And this is where things get interesting.

Because Private Endpoints are one of the most powerful — and most misunderstood — networking features in Azure.

I’ve seen teams deploy them everywhere without really understanding what they do. I’ve also seen engineers avoid them entirely because they had one bad experience with DNS.

Both approaches miss the point.

Private Endpoints aren’t just a networking toggle you flip on a resource. They’re a fundamental change in how Azure services are accessed, and they rely heavily on three pieces of infrastructure working together:

Azure networking
Azure Private Link
DNS resolution

If any of those pieces are misunderstood, Private Endpoints become fragile and painful to operate. But when they’re designed correctly, they allow Azure PaaS services to behave much more like internal infrastructure inside your network.

In this article I’m going to walk through:

what Private Endpoints actually are
how traffic flows through them
how DNS makes the whole system work
where they fit into real Azure architectures
and when they’re worth the extra complexity

This isn’t a feature overview. It’s the explanation I usually give engineers on my team when they ask:

“Should we be using Private Endpoints here?”

Because the real answer is always:

It depends on the architecture.

The Problem Private Endpoints Solve

Imagine a VM connecting to a storage account without a private endpoint.

The flow looks like this:

Even though traffic usually stays inside Microsoft’s backbone, the service itself is still publicly reachable.

The DNS record resolves to a public IP.

Your firewall rules restrict access, but the service still exists on a public interface.

This means:

The service can be scanned
It is technically internet exposed
Security teams are uncomfortable with it

What organizations want instead is something that behaves like a traditional network.

That’s exactly what Private Endpoints enable.

What Azure Private Endpoints Actually Are

A Private Endpoint is simply:

A network interface with a private IP address inside your VNet that represents an Azure service.

When you create one, Azure deploys a NIC inside your subnet.

Example:

Subnet: 10.10.4.0/24
Private Endpoint NIC
IP: 10.10.4.5

This NIC becomes the entry point into the Azure service.

Your applications connect to that private IP instead of the public endpoint.

The connection then travels across Azure’s internal Private Link infrastructure to the actual service.

The Real Architecture Behind Private Endpoints

There are three critical pieces working together.

1. Private Endpoint NIC

This exists inside your VNet.

10.10.4.5

2. Azure Private Link

Private Link carries traffic internally through Azure’s network.

Private Endpoint NIC → Private Link → Azure Service

3. Private DNS

DNS redirects service names to the private IP.

If DNS is wrong, the connection bypasses the private endpoint entirely.

This is why most Private Endpoint outages are DNS problems, not networking problems.

Network Flow With Private Endpoints

Once configured correctly, the traffic path looks like this:

The service is now reachable only from networks that can reach the private IP.

Private Endpoints vs Service Endpoints

Engineers often confuse these two features.

They solve different problems.

Service Endpoints

Service endpoints allow traffic from your VNet to reach Azure services securely over the Azure backbone.

But the service still has a public endpoint.

Flow:

Private Endpoints

Private endpoints give the service a private IP inside your network.

Flow:

Comparison:

Feature	Service Endpoint	Private Endpoint
Public endpoint exists	Yes	No
Private IP in VNet	No	Yes
DNS changes required	No	Yes
Operational complexity	Low	Higher
Network isolation	Moderate	Strong

For many workloads, service endpoints are sufficient.

Private endpoints are used when you want complete removal of public access.

Enterprise Architecture Pattern

In production environments, private endpoints rarely live alone.

They are usually part of hub-and-spoke architectures.

Key architectural decisions:

DNS centralized in the hub
Private endpoints deployed near workloads
VNets linked to shared private DNS zones
Traffic stays entirely inside Azure backbone networking

DNS: The Most Important Part

If you remember nothing else from this article, remember this:

Private Endpoints are fundamentally a DNS feature.

Without DNS working correctly, the private endpoint is never used.

Example DNS record:

privatelink.blob.core.windows.net

Private DNS Zone entry:

mystorage.blob.core.windows.net → 10.10.4.5

If DNS returns the public address:

52.x.x.x

then your private endpoint is completely bypassed.

Hybrid Connectivity Challenges

Things become more complex in hybrid environments.

Consider this architecture:

On-prem DNS must forward Private Link zones.

Example conditional forwarder:

*.privatelink.database.windows.net

Without this, on-prem systems resolve the public endpoint instead of the private one.

Terraform Example

			
resource "azurerm_private_endpoint" "storage" {
  name                = "pe-storage-prod"
  location            = azurerm_resource_group.rg.location
  resource_group_name = azurerm_resource_group.rg.name
  subnet_id           = azurerm_subnet.private_endpoints.id
  private_service_connection {
        name                           = "storage-connection"
        private_connection_resource_id = azurerm_storage_account.sa.id
        subresource_names              = ["blob"]
        is_manual_connection           = false
  }
}

		

Most organizations deploy private endpoints using infrastructure as code.

This creates:

Private endpoint NIC
Service connection
Network mapping

But it does not automatically configure DNS correctly unless you also deploy private DNS zones.

Common Production Problems

After deploying these environments repeatedly, the same problems show up again and again.

1. DNS Misconfiguration
The most common issue.
Engineers forget to link VNets to private DNS zones.

2. Disabling Public Access Too Early
Teams often do this:

Create Private Endpoint
Disable public access
DNS not working

Result:
Service unreachable
CI/CD Systems Lose Access
Build systems outside the VNet cannot reach the service anymore.

Common victims:

GitHub Actions
CircleCI
SaaS pipelines

SaaS Integrations Break

Many SaaS tools require public endpoints unless they support Azure Private Link.

When You Should Use Private Endpoints

Private Endpoints are ideal for:

Regulated Environments

Common requirements:

NIST 800-171
FedRAMP
HIPAA
Financial compliance

These frameworks often require private network access to data services.

Internal Platforms

Private endpoints work well for:

internal APIs
enterprise platforms
internal data pipelines

Sensitive Data Stores

Typical services protected with Private Endpoints:

Azure SQL
Storage Accounts
Key Vault
Cosmos DB

When Not to Use Private Endpoints

They introduce real complexity.

Avoid them when:

Simpler Security Is Enough

Firewall + identity may be sufficient.

Development Environments

They slow engineers down.

Global Public Services

If your service must be accessed globally by unknown clients, private endpoints add friction.

Lessons Learned

After designing and operating multiple Azure platforms, a few rules consistently hold true.

Design DNS First
Private endpoints should never be the first step.
DNS architecture must exist first.

Use Dedicated Subnets
Create a dedicated subnet for private endpoints.

Standardize the Pattern
Use Terraform modules so every deployment behaves the same.

Do Not Use Them Everywhere
One of the biggest mistakes engineers make is deploying private endpoints for everything.

Architecture is about balance, not maximum security features.

Final Thoughts

Azure Private Endpoints fundamentally change how secure cloud architectures are built.

They allow Azure PaaS services to behave like internal infrastructure, dramatically reducing public exposure.

But they also introduce complexity:

DNS architecture
network dependencies
operational overhead

Good engineers don’t blindly deploy features.

They understand how the system actually works and choose the right tool for the job.

Private Endpoints are powerful — when used deliberately.