12.11. Configuration Files
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## 12.11. Configuration Files

### 12.11.1. `/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.
`/etc/namedb` | Default location for named(8) data. Normally `named.conf` and zone files are stored here.
`/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.

### 12.11.2. Hostnames

#### 12.11.2.1. `/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.

#### 12.11.2.2. `/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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