no flag set.
The default value from Networkmanager global configuration is used. If such value is unset or still zero, the DHCP request will use standard FQDN flags, i.e. nm_dhcp_hostname_flag_fqdn_serv_update and nm_dhcp_hostname_flag_fqdn_encoded for IPv4 and nm_dhcp_hostname_flag_fqdn_serv_update for IPv6.