11.8. Configuration Files
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## 11.8. Configuration Files

### 11.8.1. `/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.

### 11.8.2. Hostnames

#### 11.8.2.1. `/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.

#### 11.8.2.2. `/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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