I have SBS2003 in my network as a domain controller. I want to setup Linux Vyatta router with DHCP server and DNS forwarding (relay) enabled. How to do that? When I enable DHCP/DNS server clients will receive vyatta DNS and I think clients will not be able to connect to my domain. Am I right?
I don't know why you'd want to do this in light of the fact that you're running SBS, which is intended to fill the DHCP/DNS roles, but if you must then make sure that the DNS server you choose is capable of hosting DNS zones and supports SRV DNS records (rather than being just a DNS resolver\forwarder such as a router or firewall would be). The DC must register AD specific SRV records with the DNS server and the clients must be able to find those records when querying the DNS server. Otherwise you're going to have a non-functioning domain.