Clicking the Validate button sends an HTTP GET request to the Uniform Resource Locator (URL) that is specified in the Federation Server box. If you entered a computer name (for example, FS1 or FS1.adatum.com) in this box, the validation process will create a URL based on that name (for example, https://FS1.adatum.com/adfs/fs/federationserverservice.asmx), and it will check for invalid characters before sending the URL to the federation server. If the HTTP GET request returns an error, validation fails. In the case where validation fails, you can proceed with the installation of this role service and then correct this value at a later time.