Topic: Public DNS Modify

[MCD]

Dear fellows,
I have conf. my e-smith to public DNS as name server for my domain. I have change the ipchains policy a bit as:
{
$OUT .= << 'HERE';
/sbin/ipchains --append input -p udp -d $OUTERNET 53 -j ACCEPT
/sbin/ipchains --append output ! -y -p udp -d $OUTERNET 53 -j ACCEPT HERE
}

because outsider cannot read my external DNS records to find my server.
Is that secure for me to do that like above?
Your advise is much appreciated.

MCD