Configuring bind not to use unprivileged ports?

[Angel Tsankov]

I'm using bind 9.3.1 on a linux system running kernel version 2.6.11.12. I added the following line to the options statement in the 
named.conf file:
query-source address * port 53
After that, I restarted bind but it still performs queries using UDP on unprivileged ports (1024-65535).

I need is to configure bind to use well defiend ports so that I can then configure iptables to allow outgoing DNS queries and 
incoming DNS replies. Besides, I prefer not to open all unprivileged ports so I tried the query-source option above but without 
success. Can anyone help me?

P.S. I here's the complete named.conf file in case it is needed:

options {
 directory "/etc/namedb";
 pid-file "/var/run/named.pid";
 statistics-file "/var/run/named.stats";
 allow-query { 0/0; };
 query-source address * port 53;
};

zone "." {
 type hint;
 file "root.hints";
};

zone "0.0.127.in-addr.arpa" {
 type master;
 file "pz/127.0.0";
};