Enabling forward rule in DNS Server

If server is used only for forward requests:

options {
        .
        .
        
        allow-query     { localhost; any; };
        recursion yes;
        forward only;
        .
        .
        
        dnssec-enable yes;
        dnssec-validation no;
        .
        .
        forwarders {
                8.8.8.8;
                8.8.4.4;
        };

};

If DNS server has other forward and reverse zones and you also want to add forward zone based on condition, for example, all requests related to example.com should be forwarded to server2,

options {
        .
        .
        
        allow-query     { localhost; any; };
        recursion yes;

        dnssec-enable yes;
        dnssec-validation no;
        .
        .
        

};


zone "." IN {
        type hint;
        file "named.ca";
};

zone "krishna.com" IN {
        type master;
        file "krishna.fwd.zone";
        };

zone "example.com" {
    type forward;
    forward only;
    forwarders { DNS_Server2; };
};