IP address was given 200.1.2.64 2 bits are chosen from host id
as we can see it is of class c(192-223)so 24 bit NID+8 bit HID
as you say 2 bit for subnet from HID so SUBNET MASK:-255.255.255.192
IP 200.1.2.2 CLASS C (192-223)so 24 bit NID+8 bit HID
because NID+SID=bits in the subnet mask
firstly tell how many bits are chosen from host id for subnet??