Compatible Systems 5.4 Appendices 279, Chart 3 Subnetted Class C Host Ranges, Broadcast Addresses

Appendices 279

SUBNET MASK	HOST RANGES
255.255.255.0	1-254 (traditional C)
255.255.255.128	1-126, 129-254
255.255.255.192	1-62,65-126,129-190,193-254
255.255.255.224	1-30,33-62,65-94,97-126,
	129-158,161-190,193-222,
	225-254
255.255.255.240	1-14,17-30,33-46,49-62,
	65-78,81-94,97-110,
	113-126,129-142,145-158,
	161-174,177-190,193-206,
	209-222,225-238,241-254
255.255.255.248	1-6,etc.

Chart 3: Subnetted Class C Host Ranges

ϖNote: The lowest calculated address in each range (0 in the traditional C range) is not shown, cannot be used, and is skipped in the chart. The highest address in each range (255 in the traditional C range) is also not shown, and is the broadcast address for the subnet.

With each mask above, the 1’s in the binary value represent the network portion, and the 0’s represent the host portion (128 is 10000000, 192 is 11000000, etc.). As you use more bits to represent the network portion, fewer bits are left to use as host addresses.

The same idea can be extended to Class A and Class B networks.

Broadcast Addresses

The broadcast address is the address to which devices send packets meant for all other devices. All devices “listen” for broadcasts in addition to their own address. Address Resolution Protocol (ARP) packets and routing information are examples of packets sent to the broadcast address. Most often, the broad- cast address is the last address in the network (or subnet) with the host portion being all 1’s binary (some networks use 0.0.0.0 or 255.255.255.255, however.). Below are some examples of broadcast addresses.