Here's an example configuration where all VMs are configured for NAT.
Virtual Network Editor:
DHCP disabled for NAT
For the example I assume the NAT subnet being 192.168.100.x. You may modify this if you want.
DC:
IP address: 192.168.100.10
Subnet mask: 255.255.255.0
Gateway: 192.168.100.2
DNS server: 127.0.0.1
DHCP server configuration:
Range: 192.168.100.150 ... 200
Subnet: 255.255.255.0
Gateway: 192.168.100.2
DNS server: 192.168.100.10
DNS server configuration:
DNS forwarding to: 192.168.100.2 (for URLs other than the own domain)
Other servers or systems with static IP settings:
IP address: 192.168.100.11 ... 149
Subnet mask: 255.255.255.0
Gateway: 192.168.100.2
DNS server: 192.168.100.10
Clients:
Networking set to automatic.
This way the DC will be the only DHCP and DNS server, but each VM will be able to access the Internet directly. And since the DC is the primary DNS server your AD will work properly.
André