DNS/DHCP

Our current network has 2 DC’s. One is primary DNS and other secondary and one is our DHCP server. We are an IBM iseries shop so that means that both our DC’s are in the same box but diffrent cards. We are thinking this is not a great idea if the “box” crashes. So we have added another external DC to the network. Can I add a third DNS server and a second DHCP to this new external DC for DR purposes. I would also make it a Global Catalogue server.