shutting up logs

[Nick Edwards]

 skipping nameserver 'ns5.concord.org' because it is a CNAME, while
resolving '210.128-25.119.138.63.in-addr.arpa/PTR'

I have logs grow by about 30 megs a day with pretty much only this in
it (of course not always same remote server), how do I shut this up ?

My logging statments are

logging {
        category lame-servers { null; };
        category edns-disabled { null; };
        category client { null; };
        category dnssec { null; };
        //      channel log_queries { file "/tmp/debug_query.log";
print-category yes; };
        //      category queries { log_queries; };
};

TIA