I have a (hypothetical) network with the following subnet addresses allocated using VLSM:
The network address is 150.200.48.0.
According to this site: http://subnet-calculator.org/supernets.php, you can calculate the required supernet mask by taking the length of the sequence of matching bits from left to right:
150.200.048.000: 10010110.11001000.00110000.00000000
...
150.200.052.092: 10010110.11001000.00110100.01011100
Longest matched: xxxxxxxx.xxxxxxxx.xxxxx---.--------
21 bits are matched, so the supernet mask will be /21.
Is this really the correct way of working this out? I assume that this calculation is correct as the supernet mask of /21 can be confirmed on various subnet mask calculators online.
For some reason I'm really struggling to find a good source for this information.
Best Answer
Yes, /21 is the largest supernet you can create containing all those subnets. You need to match the bits from left to right, completely correct.