Your master zone’s records will be queried by other computers across the Internet so they
can connect to your network services. There are several kinds of DNS records. The follow-
ing are the records that are available for configuration by Server Admin’s user interface:
Address (A): Also known as a machine record. Stores the IP address associated with a
domain name. An A record is created for each machine entry added to a zone.
Canonical name (CNAME): Stores the “real name” of a server when given a nick-
name or alias. For example, mail.pretendco.com might have a canonical name of
mailsrvr1.pretendco.com. A CNAME record is created for each entry in the Alias
field when adding a machine to a zone.
Mail exchange (MX): Stores the name of the computer that is used for email for a
domain. An MX record is created when you specify that a machine is a mail server.
You can have more than one MX record for your domain pointing to different
servers. Lower numbers are given priority over higher numbers when users attempt
to use the mail servers on your network.
Service (SRV): Service records store the information about various services, such as
LDAP, Jabber, and Simple Mail Transfer Protocol (SMTP). These services are then
mapped to the proper IP address and resolved to their respective domain name.
Pointer (PTR): Automatically created. Stores the domain name of a given IP address
(reverse lookup). A PTR record maps an IP address to a computer’s DNS name. The
pointer record contains the four octets of the IP address in reverse order followed by
in-addr.arpa. (For example, 10.1.17.1 becomes 22.214.171.124.in-addr.arpa.)
Mac OS X Server simplifies the creation of these records by focusing on the computer name
being added to the zone rather than the records themselves. As you add a computer record
to a zone, Mac OS X Server creates the proper pointer zone record that resolves to a certain
The term fully qualified domain name (FQDN) refers to the entire address
of a host computer. For example, “sales.apple.com” is an FQDN, whereas “sales” is a
relative domain name. To indicate that a domain name is fully qualified, add a trailing
dot to it (which Mac OS X Server v10.5 automatically does when selecting the check-
box for Fully Qualified). For example, “sales.apple.com.” indicates that this is not a
relative domain name.
DNS Zone Records 97