Supplemental Information IP Addresses
E-15
Subnet Portion
The subnet portion of the IP address represents which sub-network the address is from.
Sub-networks are formed when an IP network is broken down into smaller networks using
a subnet mask.
A router is required between all networks and all sub-networks. Generally, hosts can send
packets directly only to hosts on their own sub-network. All packets destined for other
subnets are sent to a router on the local network.
Host Portion
The host portion of the IP address is a unique number assigned to identify the host.
Network Address
A host address with all host bits set to 0 addresses the network as a whole (for example, in
routing entries).
Figure E-2: Sample Network Address
Broadcast Address
Ahostaddresswithallhostbitssetto1 is the broadcast address, meaning for “for every
station.”
Figure E-3: Sample Broadcast Address
Network and broadcast addresses must not be used as a host address; for example,
192.168.0.0 identifies the entire network, and 192.168.0.255 identifies the broadcast
address.
192.168.0.0
192.168.0.255