I've created an ASP.NET Core application on my Ubuntu machine. When I host it on an Azure Web App I noticed it was running on a Windows Server. Is it possible to host it on a Linux server instead?
Azure Web App is using Windows Server as operating system. You can always get our own computing machine, with Linux (Ubuntu or something else) and deploy whatever you need on it. See here for details: https://azure.microsoft.com/en-us/services/virtual-machines/