Download Mac OS X Server Network Services Administration

Mac OS X Server uses Berkeley Internet Name Domain (BIND) v9.4.1 for its
implementation of DNS protocols. BIND is an open source implementation and is used
by most name servers on the Internet.
DNS Zones
Zones are the basic organizational unit of DNS. Zones contain records and are defined
by how they acquire those records and how they respond to DNS requests.
There are three basic zones:
ÂÂ Primary
ÂÂ Secondary
ÂÂ Forward
Other kinds of zones are not covered here.
Primary Zones
A primary zone has the master copy of the zone’s records and provides authoritative
answers to lookup requests.
Secondary Zones
A secondary zone is a copy of a primary zone and is stored on a secondary name
server. It has the following characteristics:
ÂÂ Each secondary zone has a list of primary servers that it contacts for updates to
records in the primary zone. Secondaries must be configured to request the copy
of the primary zone data.
ÂÂ Secondary zones use zone transfers to get copies of the primary zone data.
ÂÂ Secondary name servers can take lookup requests like primary servers.
By using several secondary zones linked to one primary, you can distribute DNS query
loads across several computers and make sure that lookup requests are answered if
the primary name server is down.
Secondary zones also have a refresh interval. This interval determines how often the
secondary zone checks for changes from the primary zone. You can change the zone
refresh interval by using BIND’s configuration file. For more information, see the BIND
documentation.
Forward Zones
A forward zone directs lookup requests for that zone to other DNS servers. Forward
zones don’t do zone transfers.
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Chapter 3    Working with DNS Service