I have two ips:
1. 1.1.1.1
2. 4.4.4.4
obviously this is just an example, this is a dynamic calculator
how do i calculate number of hosts between said ips if subnet mask is irrelevant?
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Would that be the number of theorietically possible IP addresses or the number of usable IP addresses? – Guffa Nov 26 '14 at 13:53
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1You can see the IPs as 4-digit 256-based numbers. – alik Nov 26 '14 at 13:54
2 Answers
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To calculate the number of (theoretical) IP addresses you would convert each IP address to it's 32 bit integer format (which is actually what it really is), then it's just a matter of simple subtraction:
1.1.1.1 = 0x01010101 = 16843009
4.4.4.4 = 0x04040404 = 67372036
Number of addresses excluding the start and end address:
67372036 - 16843009 - 1 = 50529026
Number of addresses including the start and end address:
67372036 - 16843009 + 1 = 50529028
The number of actual usable addresses would be somewhat lower. Normally a few addresses in each C range is reserved for things like the gateway (router).
Guffa
- 640,220
- 96
- 678
- 956
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@CustomX: No. Look for example at the numbers between 5 and 7; there are 3 numbers including the start and end (5,6,7) and 1 number excluding the start and end (6). The difference between 5 and 7 is 2, so the number of numbers including start and end is 2 + 1 and the number of numbers excluding start and end is 2 - 1. – Guffa Nov 26 '14 at 15:48
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IPv4 address can be represented by an integer (4 bytes, 32 bits)
To simplify the question, assuming
- All IP addresses are usable
- One host per IP address
Then, converting both IP addresses to integer and work out the difference would be the number of hosts available.
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1This answer would be much more useful if you showed how to convert the IP address to an integer. – Jim Mischel Nov 26 '14 at 14:16