ON POOL-MANAGER VM:

- /etc/rndc.conf -
key "rndc-key" {
	algorithm hmac-md5;
	secret "jOX/cTWE4iXLTYJ5cJQYRQ==";
};
options {
	default-server  10.2.22.220;
	default-key     "rndc-key";
};

- /etc/designate/rndc.key -
key "rndc-key" {
	algorithm hmac-md5;
	secret "jOX/cTWE4iXLTYJ5cJQYRQ==";
};

- from /etc/designate/pools.yaml about rndc -
        rndc_host: 10.2.22.220
        rndc_key_file: /etc/rndc.key
        rndc_port: 953

ON BIND9 BACKEND HOST:

- /etc/rndc.key -
key "rndc-key" {
	algorithm hmac-md5;
	secret "4WEyhZ90o9plRKam2MAS9Q==";
};

- from /etc/named.conf about rndc -
include "/etc/rndc.key";

controls {
        inet * allow { any; } keys { "rndc-key"; };
};