What is the difference between inbound and out bound ip address

Question

I started learning azure one month back. We have created a app service on azure. for a app service there are two types of ip addresses generated one is Inbound and another one is outbound. Can someone please explain me why two ip address and where we can use those.

I know the same concept applies for almost every cloud based services like AWS . Do correct me if i am wrong.

Answer 1

The inbound IP address would be used as the target of anyone wishing to connect to your app. Though in an App Service you cannot connect directly with just the IP address, a Host header is required to locate the app, since the address is shared.

So if you want to configure a hostname in DNS, like yourcompany.com, you could make an A record that points yourcompany.com to the inbound IP address. That will then allow people to connect to yourcompany.com.

The outbound addresses are what other devices/services would see if your app makes an outbound network call (calls another API etc.). There is a set of them and they are all shared by other apps, your app will use one of them on each connection.

As I understand the reason there is a set of outbound addresses is to allow more simultaneous connections as each connection takes a port where it receives the responses. And there is a limited amount of ports per address.