I overlooked need for 'domain users' to be in sudoers.
domainUser@domainMemberHost:~$ sudo apt-get update
[sudo] password for domainUser:
Your password will expire in 18 days.
domainUser is not in the sudoers file. This incident will be reported.
domainUser@domainMemberHost:~$
I overlooked need for 'domain users' to be in sudoers.