Nameserver Types; Bind As A Nameserver - Red Hat ENTERPRISE LINUX 5 - DEPLOYMENT Deployment Manual

Chapter 17. Berkeley Internet Name Domain (BIND)
com, while sales is a sub-domain under example. The name furthest to the left, bob, identifies a
specific machine hostname.
Except for the hostname, each section is called a zone, which defines a specific namespace. A
namespace controls the naming of the sub-domains to its left. While this example only contains two
sub-domains, an FQDN must contain at least one sub-domain but may include many more, depending
upon how the namespace is organized.
Zones are defined on authoritative nameservers through the use of zone files (which describe the
namespace of that zone), the mail servers to be used for a particular domain or sub-domain, and
more. Zone files are stored on primary nameservers (also called master nameservers), which are
truly authoritative and where changes are made to the files, and secondary nameservers (also called
slave nameservers), which receive their zone files from the primary nameservers. Any nameserver
can be a primary and secondary nameserver for different zones at the same time, and they may also
be considered authoritative for multiple zones. It all depends on how the nameserver is configured.

17.1.2. Nameserver Types

There are four primary nameserver configuration types:
master
Stores original and authoritative zone records for a namespace, and answers queries about the
namespace from other nameservers.
slave
Answers queries from other nameservers concerning namespaces for which it is considered
an authority. However, slave nameservers get their namespace information from master
nameservers.
caching-only
Offers name-to-IP resolution services, but is not authoritative for any zones. Answers for all
resolutions are cached in memory for a fixed period of time, which is specified by the retrieved
zone record.
forwarding
Forwards requests to a specific list of nameservers for name resolution. If none of the specified
nameservers can perform the resolution, the resolution fails.
A nameserver may be one or more of these types. For example, a nameserver can be a master for
some zones, a slave for others, and only offer forwarding resolutions for others.

17.1.3. BIND as a Nameserver

BIND performs name resolution services through the /usr/sbin/named daemon. BIND also
includes an administration utility called /usr/sbin/rndc. More information about rndc can be found
Section 17.4, "Using
in
BIND stores its configuration files in the following locations:
/etc/named.conf
The configuration file for the named daemon
/var/named/ directory
The named working directory which stores zone, statistic, and cache files
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rndc".