Writing hosts and networks Files
After you have subnetted your network, you should prepare for some simple
sort of hostname resolution using the /etc/hosts
file.
If you are not going to use DNS or NIS for address resolution, you have to put
all hosts in the hosts
file.
Even if you want to run DNS or NIS during normal operation, you should
have some subset of all hostnames in
/etc/hosts
. You should have some sort of name
resolution, even when no network interfaces are running, for example,
during boot time. This is not only a matter of convenience, but it
allows you to use symbolic hostnames in your network
rc
scripts. Thus, when changing IP addresses, you
only have to copy an updated hosts
file to all
machines and reboot, rather than edit a large number of
rc
files separately. Usually you put all local
hostnames and addresses in hosts
, adding those of
any gateways and NIS servers used.[29]
You should make sure your resolver only uses information from the
hosts
file during initial testing. Sample files
that come with your DNS or NIS software may produce strange
results. To make all applications use /etc/hosts
exclusively when looking up the IP address of a host, you have to edit
the /etc/host.conf
file. Comment out any lines
that begin with the keyword order
by preceding them with a hash sign,
and insert the line:
order hosts
The configuration of the resolver library is covered in detail in Chapter 6.
The hosts
file contains one entry per line, consisting of an IP address, a ...
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