In the previous chapter, we have seen how a Proxmox GUI looks like and set up a basic cluster, which we are going to use for hands-on learning of Proxmox. In this chapter, we will look at how configuration files hold a Proxmox virtualization platform together, files to be used for advanced configuration, and how to troubleshoot a Proxmox platform. Proxmox is built on Debian Linux, which is very stable with a large active community. So, it inherited the heavy dependency on configuration or the .conf files as we Linux users lovingly like to call them. The Proxmox GUI provides you with the ability to manage a cluster, but does not provide direct access to any configuration files. Any direct changes by an advanced user have to be done through CLI. Commonly used scenarios such as adding special arguments in configuration files are also done through CLI. In this chapter, we will look at the following topics: