DNS zones are categorized by where information is stored, whether they are able to be written to, and the type of data they send and receive. Zones can be kept in an Active Directory or in text files. Primary Zones- are a zone that hosts a read and writes copy of the DNS zone in which records are produced and administered. Only one primary server per zone is allowed, and only this server loads and hosts the master copy of the zone. In addition, this server is also the only one allowed to process dynamic updates and zone changes. The primary server is generally located in a readily accessible location to allow administration of the zone file. Secondary Zones- One or more servers can be used to store a read-only copy of the primary DNS zone. Information is received from the primary through a zone transfer, which copies the zone file from the primary server to the secondary server. These zone transfers can be full--meaning it transfers the complete zone contents each time or incremental meaning it transfers only changed information since the last transfer. Stub Zones- Windows Server 2008 can also be configured as stub zones. These servers maintain a copy of the zone that only contains records necessary to identify authoritative DNS servers for its zone. Think of it as a pointer used to provide DNS resolution efficiency. Using the stub zones list of name servers, a DNS server can resolve queries without querying the Internet or other internal root servers