query fail in Bind 9.2.0

[AlbertLi]

Hi All:

My DNS is Bind9.2.0 and I create many zone in named.conf like bellow.

zone "mnc022.mcc404.gprs" {
type forward;
forwarders {202.123.213.94; 203.208.133.110;};
};

There are four master DNS in network and all copy the same named.conf. When nslookup to check these zone, two of DNS can reply address from 202.123.213.94; 203.208.133.110 but other two of DNS can't.

why? any log need for investigation?

Please help and thanks a lot.

br.
Albert