While trying to ping one backend instance via other backend instance’s SSH, do we use the former’s internal IP address or the external IP address? Because when I tried to ping in the SSH with the external IP address, it didn’t go through. While using an internal IP address, it worked. So now I am confused. Thanks in advance.
Because you don’t allow external/public traffic from outside the network to your backend instances, you can’t connect to the external IP. When SSH’d onto a frontend server, you use the internal IP which is on your "local" network because you’ve only allowed traffic that way and not via the public web.