what is the behavior of global forwarders

[kalyanasundaram S]

>>  global {
>>   forward only;
>>   forwarders {1.2.3.4; };
>>   ......
>>   ....
>>  }
>> 
>> ..
>> zone "example.com" in {
>>    type forward;
>>    forward first;
>>    forwarders { 3.3.3.3; };
>> };
>> 
>> this 3.3.3.3 does not exist. (it is a stand alone setup- so there is no
>> root server access,and 1.2.3.4 is alive in that stand alone setup) I
>> queried for some client in example.com. What i expected was that it is
>> not able to contact 3.3.3.3 so it should go for global forwarders(in
>> this case 1.2.3.4) . But it looks for root server and said connection
>> time out.
>> 
>> then again i had
>> zone "example.com" in {
>>    type forward;
>> };
>> i expected atleast now it should go for global forwarders. But again the
>> same.
>> 
>> what is default behaviour of global forwarders. Where it is used? how do
>> i configure my dns to go for global forwarders when the forward zone
>> forwarders is not available?
>> 
>> is it a bug or am i missing some option to set
>> 
> Forwarders are not cumulative. The list of forwarders you define at a
> given zone level overrides any forwarders you may or may not have
> defined at ancestor zone levels which in turn override the global
> forwarders. If you want the global forwarders to be used
> *in*addition*to* some set of zone-specific forwarders, then add them to
> the list.
> 
> Note that some versions of BIND 9 work through the forwarders list
> *sequentially*, so if you're running one of those versions, you might
> want to give some thought as to the order of the list. Other versions of
> BIND 9 choose forwarders based on an adaptive algorithm which keeps
> track of how quickly the respective forwarders respond to queries. For
> those versions, the order in which the forwarders are defined is
> irrelevant.
> 
> - Kevin

Well, thaanks a lot for answering me.
so what ever is there in global level will be overridden by the zone level declaration.
forwarders {1.2.3.4; }; at global level is overridden by forwarders {3.3.3.3; }; at zone level and the policy also overridden from "only" to "first". Am i correct?

But again 

zone "example.com" in {
    type forward;
 };
These statmenet should inherit the forwarders and the policy from global and go to 1.2.3.4 for the query right?
It should become like 
zone "example.com" in {
    type forward;
    forward only;
    forwarders { 1.2.3.4}; 
 };
Is that the correct way heppening inside?

This is not happenening it gives ms NXDOMAIN error and look for root servers?
Please help me to figure out what is happening?

Thanks ,
  -"kalyan"