I know subdomains can be setup as wildcards, CNAME and A-records, but right now I use A-record for the subdomains. To just get it going we will consentrate of just getting it working with the following configuration.

Domain: example.tld
Subdomains: mail, admin, mysql
IP: 1.2.3.4

Now we will start by adding the domain to the named.conf – Though it might not be present at this path you might need to search for it. (Using for example webmin would help you show all configuration files).

# vi /etc/named.conf

Add a new zone to named.conf

zone “example.tld” {
type master;
file “/var/named/example.tld.hosts”;
};

Save the configuration

Push escape, then : x

The next step is creating the DNS records.  Add a new file to bind.

# vi /var/named/example.tld.hosts

In this file you will create your DNS-records.

$ttl 15m ; TTL Might be smart to have at 15 minutes until your conf are ok
example.tld. IN SOA ns.example.tld. user.example.tld. (
123456789 ;An unique number
86000 ;Refresh rate in seconds
7200 ;Update Retry in seconds
3600000 ;Expiry in seconds
600 ; minimum in seconds
)

example.tld. IN NS ns.example.tld.
example.tld. IN A 1.2.3.4
www.example.tld. IN CNAME example.tld
mail IN A 1.2.3.4
admin IN A 1.2.3.4
mysql IN A 1.2.3.4
mail.example.tld. IN MX 1 example.tld.

Now save the file and restart BIND

# service bind restart