Samba KDC Settings
From SambaWiki
Samba defaults kerberos tickets expiry values to the following
in some environments it might not be practical that the user TGT expire after 10 hours.
Samba 4's KDC ticket life can be controlled using the parameters in smb.conf the values take integer values and the values should be the hours the tickets should be valid.
kdc:service ticket lifetime
kdc:user ticket lifetime
kdc:renewal lifetime