Custom DNS settings for different applications

Hi,


I have a particular use case where I need some advice. The question is regarding the following settings in the krb5.conf file:

dns_canonicalize_hostname

dns_lookup_realm
dns_lookup_kdc

I have an application A,  which needs the above mentioned settings to be true for the context it uses. 
Then there is application B which needs to block all DNS queries for performance reasons as DNS queries are costly.

According to my understanding this can be achieved in following ways:

1] Programmatically by using functions like krb5_set_dns_canonicalize_hostname (). But, such kinds of functions are not present for all the above settings.
2] By using different configuration files for different applications. But, I'm not sure if this is possible as I  couldn't find appropriate APIs.
3] By using different sections in same configuration file for different applications. Not sure if this is possible either.

Can someone help me with what are the practical options I have for achieving the end goal? 
Personally, I would have liked to be able to do something like option 3 mentioned above.

I'm currently using heimdal-1.4.1rc2 source.

Thanks,

Jaideep