Installing and Administering Internet Services

78 Chapter3
Configuring and Administering the BIND Name Service
Overview of the BIND Name Service
transport software will select an interface for outbound traffic according
to the target IP address and use that interface consistently, regardless of
the interfaces on which it is receiving inbound traffic from the target IP
address.
Round-robin address cycling is enabled by default. However, with BIND
4.9.3, if you do not want to use this feature, you can disable it by adding
the following entry to the named boot file, /etc/named.boot:
options no-round-robin.
How BIND Resolves Host Names
Because complete domain names can be cumbersome to type, BIND
allows you to type host names that are not fully qualified (that is, that do
not contain every label from the host to the root and end with a dot). This
section describes how the name server resolves host names.
NOTE It is always correct to use a name that contains all of the labels from the
host to the root and does not end with a dot. Names that end in a dot are
not allowed in the following places: mail addresses, the hostname
command, and network-related configuration files. Names that contain
all of the name components and end in a dot are used with commands
like nslookup, ping, and telnet, to facilitate the lookup process.
• If the input host name ends with a dot, BIND looks it up as is,
without appending any domains to it.
• If the input host name contains at least the number of dots specified
by the ndots option in the /etc/resolv.conf file, BIND looks it up
as is, before appending any domains to it. (The default value of ndots
is 1, so if the input host name contains at least one dot, it will be
looked up as is before any domains are appended to it.)
• If the input host name consists of a single component (contains no
dots), and you have set up a host aliases file, BIND looks in your
aliases file to translate the alias to a fully qualified host name.
You can create a host aliases file for frequently typed host names, like
the following example file:
john zircon.chem.purdue.edu
melody fermata.music.purdue.edu