12.8. Configuration Files

12.8. Configuration Files
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12.8.1. `/etc` Layout

There are a number of directories in which configuration information is kept. These include:

`/etc`	Generic system-specific configuration information.
`/etc/defaults`	Default versions of system configuration files.
`/etc/mail`	Extra sendmail(8) configuration and other MTA configuration files.
`/etc/ppp`	Configuration for both user- and kernel-ppp programs.
`/usr/local/etc`	Configuration files for installed applications. May contain per-application subdirectories.
`/usr/local/etc/rc.d`	rc(8) scripts for installed applications.
`/var/db`	Automatically generated system-specific database files, such as the package database and the locate(1) database.

12.8.2. Hostnames

12.8.2.1. `/etc/resolv.conf`

How a FreeBSD system accesses the Internet Domain Name System (DNS) is controlled by resolv.conf(5).

The most common entries to /etc/resolv.conf are:

`nameserver`	The IP address of a name server the resolver should query. The servers are queried in the order listed with a maximum of three.
`search`	Search list for hostname lookup. This is normally determined by the domain of the local hostname.
`domain`	The local domain name.

A typical /etc/resolv.conf looks like this:

search example.com
nameserver 147.11.1.11
nameserver 147.11.100.30

Note:

Only one of the search and domain options should be used.

When using DHCP, dhclient(8) usually rewrites /etc/resolv.conf with information received from the DHCP server.

12.8.2.2. `/etc/hosts`

/etc/hosts is a simple text database which works in conjunction with DNS and NIS to provide host name to IP address mappings. Entries for local computers connected via a LAN can be added to this file for simplistic naming purposes instead of setting up a named(8) server. Additionally, /etc/hosts can be used to provide a local record of Internet names, reducing the need to query external DNS servers for commonly accessed names.

# $FreeBSD$
#
#
# Host Database
#
# This file should contain the addresses and aliases for local hosts that
# share this file.  Replace 'my.domain' below with the domainname of your
# machine.
#
# In the presence of the domain name service or NIS, this file may
# not be consulted at all; see /etc/nsswitch.conf for the resolution order.
#
#
::1			localhost localhost.my.domain
127.0.0.1		localhost localhost.my.domain
#
# Imaginary network.
#10.0.0.2		myname.my.domain myname
#10.0.0.3		myfriend.my.domain myfriend
#
# According to RFC 1918, you can use the following IP networks for
# private nets which will never be connected to the Internet:
#
#	10.0.0.0	-   10.255.255.255
#	172.16.0.0	-   172.31.255.255
#	192.168.0.0	-   192.168.255.255
#
# In case you want to be able to connect to the Internet, you need
# real official assigned numbers.  Do not try to invent your own network
# numbers but instead get one from your network provider (if any) or
# from your regional registry (ARIN, APNIC, LACNIC, RIPE NCC, or AfriNIC.)
#

The format of /etc/hosts is as follows:

[Internet address] [official hostname] [alias1] [alias2] ...

For example:

10.0.0.1 myRealHostname.example.com myRealHostname foobar1 foobar2

Consult hosts(5) for more information.

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