Sybot doesn't check any authentication. When starting a job, Skybot asks 'su' to verify a user's credentials, and 'su' will use the appropriate means defined on the system.  The SFTP server works the same way - when out software connects to the SFTP server, our software passes over the provided credentials, and it's up to the SFTP server to decide how it's going to validate those credentials.  If the SFTP server has been told to only check /etc/passwd, then an AD login won't work.