Linux DNS Server

[amasso]

Hello,

I'm trying to configure a Linux server to act as a DNS server. Below is

my config files:


File: "/etc/named.conf"


zone "my-domain.com" {
        type master;
        file "/var/lib/named/my-domain.com.hosts";
        allow-transfer { Slave Server; };
        };
zone "XXX.XX.XX.in-addr.arpa" {
        type master;
        file "/var/lib/named/XXX.XX.XX.in-addr.arpa";



};


File: "/var/lib/named/my-domain.com.hosts"

$ttl 38400
my-domain.com.     IN      SOA     my-domain.com. admin.my-domain.com.
(
                        2006041804
                        10800
                        3600
                        604800
                        38400 )
my-domain.com.     IN      NS      ns1.my-domain.com.
my-domain.com      IN      NS      ns2.my-domain.com.
my-domain.com.     IN      A       MyServerIP


mail.my-domain.com.        IN      CNAME   my-domain.com.
my-domain.com.     IN      MX      10 mail.my-domain.com.
www                     IN      CNAME   my-domain.com.
ftp                     IN      A       MyServerIP
ns1                     IN      A       MyServerIP
ns2                     IN      A       SlaveServerIP


File: "var/lib/named/XXX.XX.XX.in-addr.arpa"


$ttl 38400
my-domain.com.     IN      SOA     my-domain.com. admin.my-domain.com.
(
                        2006041804
                        10800
                        3600
                        604800
                        38400 )


my-domain.com.     IN      NS      ns1.my-domain.com.


XX      PTR     ns1.my-domain.com


BIND is running on the server. If I use dig, host & ping from the local

server all information returns correctly.



>From an external machine I can't ping ns1.my-domain.com.


Am I doing something wrong? 

Please advice. 


Thanks