Problems with reverse DNS pointing to unknown hostname

I am trying to create nameservers in my new OpenVZ VPS. It is a box running debian and I have installed webmin.

When I check if the primary nameserver is working I get the following message:

Reverse for xx.10.xxx.11 points to an unknown host name (xx.10.xxx.11.customer.XXXXXXXXXXXXXX.com).

I can't find any PTR records that point to customer.XXXXXXXXXXXXXX.com

In the master zone I have created there are no PTR records, so where does this information come from?

If I check is the /etc/bind/named.conf file:

zone "localhost" {
    type master;
    file "/etc/bind/db.local";
};

zone "127.in-addr.arpa" {
    type master;
    file "/etc/bind/db.127";
};

zone "0.in-addr.arpa" {
    type master;
    file "/etc/bind/db.0";
};

zone "255.in-addr.arpa" {
    type master;
    file "/etc/bind/db.255";
};

include "/etc/bind/named.conf.local";

Why are there so many master zones? Are they needed?

Content of /etc/bind/named.conf.local

zone "XXXXXX.net" {
    type master;
    file "/var/lib/bind/XXXXXXX.net.hosts";
    }; 

Are there any other places where information is stored?