AWS PrivateLink

AWS PrivateLink provides private connectivity between VPCs and supported AWS services, partner services, or customer-hosted services using interface VPC endpoints that keep traffic off the public internet. It operates by creating interface endpoints (Elastic Network Interfaces) in a consumer VPC that route traffic over the AWS network to a service endpoint in the provider VPC or to supported AWS services. It normally fits as a VPC-level networking component to provide private, IP-based access without exposing services to public IP addresses.

🗂 Resource Category

Networking and Content Delivery

🧠 Exam Memory Hook

Think: Private VPC connectivity + interface ENIs + no public internet = AWS PrivateLink

📖 Ownership

Classification: AWS Managed Service

AWS responsibilities: AWS operates and patches the underlying physical network infrastructure and the PrivateLink control plane that provisions and manages interface endpoint lifecycle; AWS maintains availability of the regional PrivateLink service and the parts of AWS-managed services that are exposed via PrivateLink according to those services' models. AWS also controls the underlying networking fabric and the platform that attaches ENIs into consumer VPCs. AWS does not manage or patch customer EC2 instances, customer-managed load balancers or customer-hosted services that are used as endpoint service backends.

Customer responsibilities: The customer creates and configures interface endpoints in their VPC subnets, assigns and controls security groups and endpoint policies, configures DNS (private hosted zones or Private DNS option), monitors endpoint metrics and logs, and secures the service hosts when offering an endpoint service. If hosting an endpoint service, the customer (or provider account) deploys and maintains the Network Load Balancer and the backend hosts, configures permission for consumer accounts, and monitors and patches those hosts and applications.

Patching responsibilities: AWS patches the AWS-owned physical infrastructure and the PrivateLink control plane. Customers are responsible for patching guest operating systems, application runtimes, libraries, dependencies, and the applications that run on EC2, containers, or other compute used by an endpoint service; customers also maintain and patch any customer-managed Network Load Balancer backends. When PrivateLink is used to access other AWS-managed services, those services are patched by AWS according to their own service models.

🏗 Typical Architecture

💡 Top 5 Features

Creates interface VPC endpoints implemented as ENIs in consumer subnets for private IP-based connectivity to services.
Allows providers to expose services as endpoint services that consumers can connect to without VPC peering or public IPs.
Supports endpoint policies to restrict which API actions and principals can use an endpoint.
Offers an optional Private DNS configuration so the service DNS name can resolve to endpoint IPs inside the VPC.
Integrates with Network Load Balancer as the typical supported backend for provider endpoint services.

✅ Top 5 Use Cases

Securely connect VPC-hosted applications to third-party SaaS or partner services without routing traffic over the public internet.
Provide cross-account private access to a centralized service (for example authentication or telemetry) by offering it as an endpoint service.
Expose a privately hosted API or microservice to other AWS customers or accounts without creating public endpoints or VPC peering.
Restrict service access to VPC-local private IP addresses and security groups instead of using Internet Gateways or NAT.
Enable private access to supported AWS service endpoints when interface endpoints are required instead of gateway endpoints.

🏗 Architecture Placement

AWS PrivateLink sits at the VPC level as interface VPC endpoints (ENIs) placed in consumer subnets; resources in the consumer VPC (EC2, containers, Lambda in VPC) send requests to the endpoint IPs which forward traffic to a provider endpoint service typically fronted by a Network Load Balancer in a provider VPC or to supported AWS services. DNS can be configured so service names resolve to endpoint IPs inside the VPC. It is regional and VPC-scoped, and access is controlled by security groups and endpoint policies.

🎯 Commonly Used With

- Amazon VPC
- Amazon EC2
- Elastic Load Balancing
- Amazon Route 53
- AWS Identity and Access Management

🌍 5 Real-World Examples

A financial services application in a customer VPC connects to a third-party fraud-detection SaaS over PrivateLink to keep sensitive traffic off the public internet for compliance reasons.
A healthcare analytics vendor exposes its API as an endpoint service so hospital customers can access it privately without public endpoints.
A retail company exposes an internal authorization microservice from a central AWS account via PrivateLink so multiple application teams in other accounts can call it privately.
A telecommunications operations team offers a telemetry ingestion API as an endpoint service backed by NLB and EC2 so partner networks can push metrics without internet exposure.
A government agency restricts access to a controlled data-processing service by using PrivateLink endpoints and security groups to enforce network-level access from approved VPCs.

🎓 AWS Exam Clues

Choose PrivateLink when the requirement is private, IP-based access to a service without using the public internet or public IPs.
PrivateLink is a good option for cross-account service access when you do not want VPC peering or route table exposure.
Look for references to interface endpoints, ENIs, endpoint policies, or provider endpoint services backed by NLB in scenario descriptions.
Consider DNS and security group configuration as key operational controls when architecting PrivateLink connectivity.
PrivateLink is regional and VPC-scoped; scenarios requiring global DNS endpoints or edge distribution may indicate a different solution.

📝 Quick Revision

AWS PrivateLink provides private, VPC-local connectivity to services using interface VPC endpoints (ENIs) so traffic does not traverse the public internet. Use it to access partner SaaS, cross-account shared services, or supported AWS services privately; consider endpoint policies, security group rules, DNS configuration, and that providers must manage their NLB and backend hosts.

🏷 Keywords

Interface VPC endpoint • ENI • Endpoint service • Private DNS • Endpoint policy • Network Load Balancer • Cross-account access • Security group • VPC-scoped • Private connectivity • Service provider • Consumer endpoint