DNS domains and zones
Under DNS, the network consists of a hierarchy of domains.
This hierarchy, referred to as the domain name space, is organized
as an inverted tree radiating from a single root, much like the UNIX
Domain name space
is the root of the tree. Final attempts at resolution occur here, if
lower-level servers do not have the requested data.
are hosts located where the tree branches, or hosts at the end of a branch:
individual computers running DNS software.
is a subtree of the domain name space, sharing its domain name
with the name of its top-most node, such as your_company.COM.
is a domain that branches off another, such as rivers.your_company.COM.
is a portion of the domain name space that is served by a primary
name server and one or more secondary name servers. A
zone may be an entire domain, a domain with all of its child domains,
or a portion of a domain.
The top level of the domain name space is fairly well defined, with
domains such as COM for corporations, GOV for
governmental organizations, and EDU for educational institutions.
Administrators build branches of the tree at individual sites by:
a domain name
with the appropriate body.
installing one or more machines as DNS servers for the domain.
configuring these servers' DNS database files to specify
the boundaries of the domain, via the
SOA (start of authority) resource record.
Name Server Operations Guide for BIND
for more information on the SOA resource record.)
propagating information about the domain upwards through the tree through
a series of zone transfers.
DNS domain and hostnames
How DNS works
© 2003 Caldera International, Inc. All rights reserved.
SCO OpenServer Release 5.0.7 -- 11 February 2003