Comparing public and private application access

Public and private access describe the network path to an application, not whether its users are trusted. A public endpoint makes the application reachable over the internet; a private endpoint limits access to a relevant network path. Neither path replaces authentication and authorisation for the application itself.

For Azure applications, named public-ingress patterns include Azure Front Door with a web application firewall (WAF) in front of Azure API Management (APIM), a global-edge pattern, and Application Gateway in front of APIM for regional ingress. On Azure, Azure Private Endpoint, using Azure Private Link, gives a service a private IP address.

For reachability, a public path can suit distributed customers and staff who need to connect from different locations. A private path can reduce direct internet exposure for back-office workloads, but access depends on the relevant network route and can be less convenient for people working on the go.

For day-to-day operation, a public path is often simpler to operate, though authentication, encryption, rate controls and monitoring still need to fit the service. A private path adds routing, DNS and client-network dependencies that the organisation needs to operate reliably.

AWS also names a private-access option: AWS PrivateLink uses VPC endpoints. AWS interface endpoints place network interfaces with private IP addresses in subnets, without public IP addresses or route-table entries to the internet.

Identity and authorisation remain application requirements on either path. A private endpoint does not, by itself, establish that a user is trusted or should be allowed to use the application.

Choose a public path when distributed customers or staff need direct reachability and the organisation can secure and monitor the internet-facing service. It can also suit variable workloads that need flexibility.

Choose a private path when reducing direct internet exposure matters, such as for a back-office workload, and the organisation can reliably manage the network and DNS dependencies. Include contractors and mobile staff when checking whether they can reach the required private network.

For Azure Private Endpoint, the service FQDN needs to resolve to its private endpoint address; it can instead resolve to a public IP or return NXDOMAIN if private DNS is not set up for the querying network. Treat that DNS dependency as part of the private-path decision.

Choose the least complicated path that meets the access requirement and can be operated reliably. Reassess it if the audience or data flow changes, while continuing to secure and authorise access to the application.

Public vs Private Application Access: Key Differences

Key Considerations for Access Choice

Choosing the Right Access Type