When a user attempts to access an Adobe software or service, the operating system queries the hosts file to resolve the hostname to an IP address. If the hostname is present in the hosts file and mapped to a non-routable IP address (e.g., 127.0.0.1 or 0.0.0.0 ), the request is effectively blocked. Adobe's Hosts File Block List contains a comprehensive list of hostnames associated with pirated software, cracks, and illicit services.