@raja11sep what he told, I totally agree with him.
If it is classless, also 20.255.0.0/16 and 20.0.0.0/8, “this 20.255.0.0/16 will fall under this n/w id 20.0.0.0/8”.
And if you think that 20.255.0.0/16 and 20.0.0.0/16, then the DBA will be 20.255.255.255 and 20.0.255.255 respectively.