There are 16 bits available; it is up to you how many of those bits you reserve for the subnet, and how many for the individual hosts within each subnet.
1
You would need at least 9 bits to borrow. Since 8 bits gives only 255 the additional bit will get you 256. Adding 256 + 128 gives you at least 384 subnets or hosts.
255.255.252.0
255.255.252.0
A class A would give you the most flexibility in terms of subnets and hosts per subnet. You could use up to 23 bits of information for subnets.
The IP address 172.30.0.0 is a private IP address in the Class B range, which has a default subnet mask of 255.255.0.0 (or /16). If you use the default mask, you can create 65,536 addresses (2^16), allowing for 65,534 usable hosts per subnet (subtracting 2 for the network and broadcast addresses). If you further subnet this address, the number of subnets and hosts per subnet will depend on the subnet mask you choose. For example, using a /24 subnet mask would give you 256 subnets with 254 usable hosts in each.
that gives you 16 subnets with 14 usable IPs for hosts that is because one is for subnet and one for broadcas in that subnet for example: 192.168.1.0/28 - subnet number 192.168.1.15 -broadcast number usable IPs for hosts - IPs between them that is 14
255.255.252.0
To calculate a subnet mask, first determine the number of subnets needed and the number of hosts per subnet. Use the formula (2^n \geq \text{number of subnets}) for subnetting and (2^h - 2 \geq \text{number of hosts}) for host calculation, where (n) is the number of bits borrowed for subnets and (h) is the number of bits left for hosts. For example, if you start with a Class C address like 192.168.1.0 and want 4 subnets, you would borrow 2 bits (since (2^2 = 4)), resulting in a subnet mask of 255.255.255.192 (or /26), which allows for 62 hosts per subnet.
254
To implement subnetting, first determine the network's requirements, including the number of subnets and hosts per subnet. Next, choose a suitable subnet mask that allows for the desired number of subnets and hosts by calculating the available bits in the IP address. Divide the IP address space into subnets based on the selected mask, ensuring that each subnet has a unique network address. Finally, configure the devices on the network to recognize the new subnets by updating their IP addresses and subnet masks accordingly.