Answer
Solution:
Given,
=>Network address = 172.30.0.0/16
=>Number of subnets required = 100
=>Minimum number of hosts per subnet = 500
The answer will be an option,
(b) 23
Explanation:
Calculating number of bits for subnetting:
=>Number of bits for subnetting = ceil(log2(number of subnets))
=>Number of bits for subnetting = ceil(log2(100))
=>Number of bits for subnetting = 7 bits
Calculating minimum number of bits for host ID:
=>Minimum number of bits for host ID = ceil(log2(number of hosts))
=>Minimum number of bits for host ID = ceil(log2(500))
=>Minimum number of bits for host ID = 9 bits
Calculating prefix length:
=>In the given network address "/16" represents the number of bits for net ID part.
=>Prefix length = net ID bits + subnet ID bits
=>Prefix length = 16 bits + 7 bits
=>Prefix length = 23 bits
=>Hence 23 bits will be required for prefix length and remaining 9 bits will be used for host ID.
=>Hence on the basis of above statements option (b) is correct and other options are incorrect because prefix length = 23
I have explained each and every part with the help of statements attached to the answer above.