As neither an expert on samba nor Active Directory, I have struggled to manage samba as an AD Domain Controller. The documentation seems to be a bit of a moving target. Luckily, some of the most important commands are somewhat self-documenting, but I still find myself needing hints. This page is a place to collect those hints.
User Management:
View a user's record: samba-tool user show username
Enable a disabled user: samba-tool user enable username
Disable password expiry for a user: samba-tool user setexpiry username --noexpiry
DNS woes:
If using samba for the purpose of SSO for virtual machine clients, you will find that dnsmasq gets installed for libvirtd and causes problems with samba. These examples will pertain to debian-style servers.
Stop dnsmasq: service dnsmasq stop; killall dnsmasq
Disable dnsmasq: update-rc.d dnsmasq disable