Explanation:

Answer: Option D. 255.254.0.0

Solution:

Hence, 10.0.0.0 is a Class A IP Address and by default, its network bit is 8 and host bit is 24.

A/Q there are 40 Subnets available and we need another 60 subnets.

It means the total subnet we need is 40+60=100

So, we have to borrow 7 bits from the host (27 = 128 Subnets). It is the number of subnets with the maximum host.

Now, let’s find the subnet mask

Count the value of all the bits borrowed from the host. Hence we have borrowed 7 bits so, (27 + 26 + 25 + 24 + 23 + 22 + 21) = 254

Therefore, the new subnet mask you will get is 255.254.0.0.