In the past I have used a couple different scenarios for DNS. On my first server - I used the data centers DNS servers. They charged me 20 per domain to setup but beyond that it was never a problem. On another server - my partner setup Plesk so that every domain acted as its own DNS server. Been using that for a couple months and don't see any problems. I know another option is to use the DNS servers at the registrar.
I am about to get 2 more servers and I am wondering what would be best for DNS? I really don't know the ins and outs of these different methods.