You are designing a distributed application for azure. the application must securely integrate with on-premises servers. you need to recommend a method of enabling internet protocol security (ipsec)-protected connections between on-premises servers and the distributed application. what should you recommend?

Azure Site-to-Site VPN

Explanation:

Distributed applications are computer softwares that run and work with each other on different computers that are registered under a network to execute a specific task.

And the method of enabling Internet Protocol security (IPsec)-protected connections between on-premises servers and the distributed application is a Site-to-Site VPN.

Azure Site-to-Site VPN gateway connection is used to securely integrate with on-premises servers. It is used to send encoded messages.

Azure Site-to-Site VPN

Explanation:

First of all what is a distributed application

According to Techopedia  

 A distributed application is software that is executed or run on multiple computers within a network. These applications interact in order to achieve a specific goal or task.  

Azure distributed applications are software that run on Azure which is a cloud base technology that not only provides an Application Hosting environment, but also a full-scale Development Platform.  

In order to understand why this answer for this question we need to also understand what an On-premises server is.

On-premises:  

This can be defined as a computer application that is always found at a company's data center instead of running it on a hosted server or in the cloud  

Now an Azure Site-to-Site VPN is the recommended method for enabling Internet Protocol security (IPsec)-protected connections between on-premises servers and the distributed application because IPsec can be used on Site-to-Site VPN, and Distributed applications can used the IPSec VPN connections to communicate.