Dúvidas DNS (Configuração)

Segui as dicas do site para configurar o DNS (HOW TO DNS) e abaixo estão meus arquivos de configuração. Como sei se o DNS está funcionando?.

lasertools.conf

"
zone "lasertools.laser.br" {
type master;
file "zone/db.lasertools";
};

zone "4.172.168.192.in-addr.arpa" {
type master;
file "zone/rev.lasertools";
};

"

db.lasertools

"
$TTL 86400
@ IN SOA lasertools.laser.br. postmaster.lasertools.laser.br. (
2003090200 ; Serial
28800 ; Refresh
14400 ; Retry
3600000 ; Expire
86400 ) ; Minimum
@ IN NS lasertools.laser.br.
@ IN NS ns.lasertools.laser.br.
lasertools.laser.br. IN A 192.168.172.4
ns.lasertools.laser.br. IN A 192.168.172.4
ftp IN A 192.168.172.4
www IN CNAME lasertools.laser.br.
mail IN A 192.168.172.4
@ IN MX 5 mail.lasertools.laser.br.
pop IN CNAME mail.lasertools.laser.br.
smtp IN CNAME mail.lasertools.laser.br.
"

rev.lasertools

"
$TTL 86400
@ IN SOA lasertools.laser.br. postmaster.lasertools.laser.br. (
2003092002 ; Serial
28800 ; Refresh
14400 ; Retry
3600000 ; Expire
86400 ) ; Minimum
@ IN NS lasertools.laser.br.
4.172.168.192.in-addr.arpa. IN PTR lasertools.laser.br.
"

named.conf

"
// generated by named-bootconf.pl

options {
directory "/var/named";
/*
* If there is a firewall between you and nameservers you want
* to talk to, you might need to uncomment the query-source
* directive below. Previous versions of BIND always asked
* questions using port 53, but BIND 8.1 uses an unprivileged
* port by default.
*/
// query-source address * port 53;
};

//
// a caching only nameserver config
//
controls {
inet 127.0.0.1 allow { localhost; } keys { rndckey; };
};
zone "." IN {
type hint;
file "named.ca";
};

zone "localhost" IN {
type master;
file "localhost.zone";
allow-update { none; };
};

zone "0.0.127.in-addr.arpa" IN {
type master;
file "named.local";
allow-update { none; };
};

include "/etc/rndc.key";
include "/var/named/primary/lasertools.conf";

"