Forwarders working differently on bind9.8 & bind9.11

[Prashasti Arora]

I have configured a new zone to forward certain queries to my application
on 2 VMs (One local and the other in my network) through a specific port. I
have 2 similar setups - they are identical, except that one uses bind9.8
and the other uses bind9.11. Configuration is also identical for both.

On the first setup (using bind9.8): the traffic I send gets distributed
uniformly.
On the second setup (using bind9.11): the traffic gets distributed barely.
99% of the traffic is sent to one VM.

I have verified that forwarding is working correctly on both, the issue is
not with the application because both VMs on each setup can handle traffic
individually, the firewall is not blocking the queries, and the
configuration is correct.

This is the zone:

zone "example.com" IN {
type forward;
forwarders { 127.0.0.1 port xxx; a.b.c.d port xxx; };
forward only;
};


Please share any other possible solutions.
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