HP-UX Reference (11i v3 07/02) - 4 File Formats (vol 8)

n
named.conf(4) named.conf(4)
(BIND 9.3)
A domain name identifies a node. Each node has a set of resource information, which may be empty. The
set of resource information associated with a particular name is composed of separate RRs. The order of
RRs in a set is not significant and need not be preserved by name servers, resolvers, or other parts of the
DNS. However, the sorting of multiple RRs is permitted for optimization purposes, for example, to specify
that a particular nearby server be tried first.
Domain servers store information as a series of resource records, each of which contains a particular piece
of information about a given domain name (which is usually, but not always, a host). The simplest way to
think of a RR is as a typed pair of data, a domain name matched with relevant data, and stored with some
additional type information to help systems determine when the RR is relevant.
Note: RRs are represented in binary form in the packets of the DNS protocol, and are usually
represented in highly encoded form when stored in a name server or resolver. The binary for-
mat is defined in the RFCs that are listed with the RR type keywords in the following Syntax sec-
tion. The owner_name is often implicit, rather than forming an integral part of the RR. For
example, many name servers internally form tree or hash structures for the name space, and
chain RRs off nodes.
Syntax
owner_name [ ttl ][class ] type rrdata
(ttl and class may be entered in either order. The
IN class and ttl values are often omitted from
examples in the interests of clarity.)
owner_name
The domain name of the owner of the information in the RR. This can be one of:
. (period)
The domain name of the DNS root name server.
@ The current origin.
domain_name
A standard domain name. If domain_name does not end with a period (.), it is
relative and the current origin is appended to it. If domain_name ends with a
period (
.), it is absolute.
blank If the first character of the record is blank, the previous owner_name is used.
ttl The Time to Live (TTL) of the RR. This field is a 32-bit integer in units of seconds and is
primarily used by resolvers when they cache RRs. The ttl defines how long a RR can be
cached before it should be discarded. See the Time to Live (TTL) and Time Specification
sections for more detail.
class A keyword, encoded as a 16-bit value, that identifies a protocol family or an instance of a
protocol. The following keywords are supported:
IN The Internet system, the default.
CH Chaosnet, a LAN protocol created at MIT in the mid-1970s. Rarely used for its
historical purpose, but reused for BIND’s built-in server information zones, for
example, version.bind .
HS Hesiod, an information service developed by MIT’s Project Athena. It is used to
share information about various systems databases, such as users, groups,
printers, and so on.
All records in a zone file must be of the same class.
type A keyword, encoded as a 16-bit value, that specifies the type of the resource in this resource
record. Types refer to abstract resources.
The following keywords are supported. Some of these listed, although not obsolete, are
experimental or historical and not in general use.
A Defines an IPv4 host address. In the IN class, this is a 32-bit IP address.
Described in RFC 1035.
A6 Defines an IPv6 host address. This can be a partial address (a suffix) and an
indirection to the name where the rest of the address (the prefix) can be found.
Experimental. Obsoleted/deprecated. Use AAAA instead. Described in RFC
264 Hewlett-Packard Company − 32 − HP-UX 11i Version 3: February 2007