I just joined an ubuntu 18.04 server to my windows domain. I want to add domain admins as sudoers on the ubuntu server. I created a file /etc/sudoers.d/domain_admins. I added %DOMAIN.COM\Domain\ Admins ALL=(ALL) ALL. When I tested a sudo command, with my domain admin, I got the message that it wasn't in the sudoers file. I checked the permissions on the file and noticed it was given 47. I did a chmod of 0440 but that did not seem to work as it's still set as 47. Any help would be appreciated.