How to calculate available network addresses for a given CIDR block?

0
votes

I have browsed a lot, but all articles seems to be focused on host-address range and not the range available for network addresses for a given CIDR block.

So let's say there are these 2 valid CIDR blocks: 10.0.0.0/16 172.31.0.0/16

Both provides the same host-address range. But does both provide the same network address range? I suppose no. But then what are those ranges? And which protocol rule mandates it?

1
networkingcidr
Given those two, you have two networks. I don't understand what you are asking. You can subnet them in many, many different ways. If you want to learn how to do that, I suggest this answer on Network Engineering. - Ron Maupin
Do not understand the question, what is the difference between host address range and range available for a given CIDR block? For both your example range is 16 bit, lower 16 bits are masked. 10.0.x.x and 172.31.x.x are the same or different? Can calculate range here ipaddressguide.com/cidr - vitalygolub
Hope this helps. For a network with CIDR block 172.31.0.0/16, what are the possible network addresses? The hosts must use least significant 16 bits (as most significant 16 bits are reserved for network address). What about a subnet? A subnet address uses least significant or most significant bits? I am really new to networking :(. - Manojkumar Khotele

1 Answers

0
votes

Once a CIDR block is allocated to a network, the network has control over only the bits reserved for host addresses. And if the subnets are to be created within this network, it has to use the available bits for addressing network address.

When you create a subnet, you specify the CIDR block for the subnet, which is a subset of the parent network's CIDR block.

Hence the no of subnets/ networks which can be created within a network with either CIDR block 10.0.0.0/16 or 172.31.0.0/16 would be same.