it's a good idea to have a zone local on each server that contains the box domain and the boxname as well as a zone that is accurate for the nameserver domains and their A entries. Just make sure they match other boxes that may be authoratative for that domain.
so let's say you have server1.yourhost.com as a host name . lets say the domain's DNS is using that same server for authoratative lookups. Obvious that you need a zone on that box that has the ns evtries as well as the box name A records. Now lets say you have a server2.yourhost.com box. It's a good idea to same zones on that box as well that are in sync with the server1 ..at least the zone that is for the "yourhost.com" domain and the nameservers using that domain. If you don't do this ..you will find that email between boxes will 550 .. reason may be if server1 gets a email from server2 ..since the box names claim to be on the same domain "yourhost" .. it will want to use the local dns zone an dif they do not match or do not contain a entry for "server2" for example it can't verify a mail server. In general sync your zones when possible. You can do this with dns clustering as well.