Information Technology Reference
In-Depth Information
hosts
—The DNS address (A type) records used for resolving hostnames
to IP addresses (not to be confused with the
/etc/hosts
file).
➤
hosts.rev
—The DNS pointer (PTR type) records used for resolving IP
addresses to hostnames.
➤
named.local
—The DNS records for the localhost or the loopback
interface.
➤
The
named.ca
,
hosts
,
hosts.rev
, and
named.local
files are typically located
under the
/var/named
directory, but can be in any directory specified by the
/etc/named.conf
file.
DNS Client
A host is configured as a
DNS client
(also referred to as a resolver) by creat-
ing the
/etc/resolv.conf
file and including the directives list in Table 16.1.
Table 16.1
The /etc/resolv.conf File Directives
Directive
Purpose
domain
domain
The
domain
in which the host is included.
nameserver
IP_address
The
IP address
of the DNS server to be used for queries.
options
option1 option2 ...
Specifies one or more options.
search
domain1 domain2 ...
The domains to search to resolve hostnames.
sortlist net1 net2 ...
In case a query receives multiple addresses, use the
address with
net1
, and then
net2
, and so on.
The following shows the contents of a sample
/etc/resolv.conf
file:
domain unixcert.net
nameserver 192.168.99.9
search unixcert.net quepublishing.com
sortlist 192.168.99.0
This
/etc/resolv.conf
file will:
Place the system in the
unixcert.net
domain.
➤
Contact the DNS server with the IP address 192.168.99.9 to resolve
hostnames.
➤
Will try to resolve a hostname as if it is in the
unixcert.net
domain. If that
fails, it will try to resolve the hostname as if it is in the
quepublishing.com
domain.
➤
