Finding the Subnet Broadcast Address: Difficult Masks
To find a subnet’s broadcast address, a similar process can be used. For simplicity, this process begins with the subnet ID, rather than the IP address. If you happen to start with an IP address instead, use the processes in this chapter to first find the subnet ID, and then use the following process to find the subnet broadcast address for that same subnet. For each octet:
Step 1. If the mask octet = 255, copy the subnet ID.
Step 2. If the mask octet = 0, write a 255.
Step 3. If the mask is neither, identify this octet as the interesting octet:
A. Calculate the magic number as 256 – mask. ...
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