What we discussed in the previous section is Classful subnet masking. A Subnetmask normally contains the host portion of the bits also. This is called Classless Inter Domain Routing (CIDR). This will enable more networks for a given class of network address. For example, allowing 3 host bits towards subnet portion in our previous IP address, will allow us to offer 2X2X2 or 8 additional subnetworks. Traditionally, all zeros, and all ones subnets are not used, and hence we are left with 6 subnets. 192.189.210.078: 1100 0000.1011 1101.1101 0010.0100 1110 Class C IP Address 255.255.255.224: 1111 1111.1111 1111.1111 1111.1110 0000 Class C subnet mask with 3 additional bits of host portion used for Subnetting. Broadcast address: 1100 0000.1011 1101.1101 0010.0101 1111 :192.189.210.95 The above is the broadcast address for a given subnet (192.189.210.078). Under Classful routing, the broadcast address would have been 192.189.210.255.
Cisco Certified Network Associate Exam,640-802 CCNA All Answers ~100/100. Daily update