If you are managing lots of domains and have DNS infrastructure that speeds across contry and continent. BIND has some nice features to help you out ( version 9 ). Master/slave configurations where masters push updates, key authentication for queries/updates split zones etc.. etc.. read the feature list. Like any software you need to keep your binaries up to date. BIND has awesome features, and IMHO is not really that hard to understand. Not to mention the copious amount of documention on using/configuring it.