Let me explain my setup.My VCN has two private subnet.
Subnet 1 : Installed domain controller with required AD ports open through security list on Subnet1 . it uses default DHCP options. DNS role installed on same server.
Subnet 2 : Installed windows instance with custom DHCP option where custom DNS points to server what I have installed in Subnet 1
Problem : When windows instance deployed in Subnet 2, it remain in work-group not joining to domain automatically. Every time, I need to manually add it.
Note: DC,DNS,and test machine can communicate each other between subnets. Please help me on how to load machine with domain joined.