Introduction

DNS is a big player on the internet.  It gives us a way to assign names to all those IP addresses out there.  This howto is going to cover installing DNS and 3 configuration examples.  Keep in mind that one server can encompass all three configurations at the same time.

Setup New Server (Optional)

I like to have dedicated DNS servers.  So you can start with a fresh server install.  Follow the HOWTO below to setup a new server.  Otherwise move on to install software.

Install Software

We will be using BIND for our DNS server.  Software is a quick install.  Type the following.
> sudo apt-get install bind9 bind9utils bind9-doc

Three DNS Configurations

I’m going to cover 3 common DNS configurations.  They are:

Caching DNS Server:
Usually a local server.  It helps speed up the DNS lookup process by storing a local cache of frequently looked up host names by clients.

Primary DNS Server:
This type of server provides authoritative answers for domains and sub domains.  Zone files contain information about the domain.

Secondary DNS Server:
This type of server is known as a slave server.  It provides redundancy to the primary DNS server.

Caching only DNS Server

Out of the box the Bind package for Ubuntu has been configured as a caching DNS server.  We can speed up lookups by forwarding them to your ISP’s DNS servers, Googles DNS server and / or other fast DNS server.  In this example I’m going to use Google’s DNS server.  We are also going to limit the clients that can use the server.

Make a backup of /etc/bind/named.conf.options
> sudo cp /etc/bind/named.conf.options /etc/bind/named.conf.options.save

Change /etc/bind/named.conf.options to look like the text below.
> sudo nano -w /etc/bind/named.conf.options

// caching only DNS server config
//
acl localclients {
  192.168.0.0/16;
  10.0.0.0/8;
  localhost;
  localnets;
};
options {
  directory "/var/cache/bind";
  recursion yes;
  allow-query { any; };
  allow-query-cache { any; };
  allow-recursion { localclients; };
  forwarders { 
    0.0.0.0;
    8.8.4.4;
  }; 
  dnssec-validation auto;
  auth-nxdomain no; # conform to RFC1035
  listen-on-v6 { any; };
};

Restart bind
> sudo service bind9 restart

Primary DNS Server

This configuration is for providing DNS for your domain name(s).  I’m only going to cover a basic domain setup.  There are a lot of configuration options for zone files.

Make a backup of /etc/bind/named.conf.options
> sudo cp /etc/bind/named.conf.options /etc/bind/named.conf.options.save

Change /etc/bind/named.conf.options to look like the text below.
> sudo nano -w /etc/bind/named.conf.options

// caching only DNS server config
//
acl localclients {
  192.168.0.0/16;
  10.0.0.0/8;
  localhost;
  localnets;
};
options {
  directory "/var/cache/bind";
  recursion yes;
  allow-query { any; };
  allow-query-cache { any; };
  allow-recursion { localclients; };
  forwarders { 
    0.0.0.0;
    8.8.4.4;
  }; 
  dnssec-validation auto;
  auth-nxdomain no; # conform to RFC1035
  listen-on-v6 { any; };
  allow-transfer { none; };
};

Edit /etc/bind/named.conf.local and add the text below.
> sudo nano -w /etc/bind/named.conf.local

zone "example.com" {
  type master;
  file "/etc/bind/db.example.com";
};

Now create /etc/bind/db.example.com and use the text below.
> sudo nano -w /etc/bind/db.example.com

$TTL 604800
@ IN SOA dns1.example.com. admin.example.com. (
          10   ; Serial
      604800   ; Refresh
       86400   ; Retry
     2419200   ; Expire
      604800 ) ; Negative Cache TTL
;

; Name servers
example.com.    IN   NS   dns1.example.com.

; A records for name servers
dns1            IN   A    192.168.1.1

; Other A records
@               IN   A    192.168.1.2
www             IN   A    192.168.1.2

Restart bind
> sudo service bind9 restart

Secondary DNS Server

This configuration is for providing DNS for your domain name(s).  I’m only going to cover a basic domain setup.  There are a lot of configuration options for zone files.

Make a backup of /etc/bind/named.conf.options
> sudo cp /etc/bind/named.conf.options /etc/bind/named.conf.options.save

Change /etc/bind/named.conf.options to look like the text below.
> sudo nano -w /etc/bind/named.conf.options

// caching only DNS server config
//
acl localclients {
  192.168.0.0/16;
  10.0.0.0/8;
  localhost;
  localnets;
};
options {
  directory "/var/cache/bind";
  recursion yes;
  allow-query { any; };
  allow-query-cache { any; };
  allow-recursion { localclients; };
  forwarders { 
    0.0.0.0;
    8.8.4.4;
  }; 
  dnssec-validation auto;
  auth-nxdomain no; # conform to RFC1035
  listen-on-v6 { any; };
  allow-transfer { none; };
};

Edit /etc/bind/named.conf.local and add the text below.
> sudo nano -w /etc/bind/named.conf.local

zone "example.com" {
  type slave;
  file "db.example.com";
  masters { 192.168.1.1; }
};

Restart bind
> sudo service bind9 restart

Conclusion

This howto was focused on configuring Bind on Ubuntu.  You will need to do research on all the options that Bind offers.