Editing Default gateway (section)

===Single router===
The following example shows IP addresses that might be used with an office network that consists of six hosts plus a router. The six hosts addresses are:
* 192.168.4.3
* 192.168.4.4
* 192.168.4.5
* 192.168.4.6
* 192.168.4.7
* 192.168.4.8
The router's inside address is:
* 192.168.4.1
The network has a [[subnet mask]] of:
* 255.255.255.0 (/24 in [[Classless Inter-Domain Routing|CIDR]] notation)

The address range assignable to hosts is from 192.168.4.1 to 192.168.4.254. TCP/IP defines the addresses 192.168.4.0 (network ID address) and 192.168.4.255 (broadcast IP address).

The office's hosts send packets to addresses within this range directly, by resolving the destination IP address into a [[MAC address]] with the [[Address Resolution Protocol]] (ARP) sequence and then encapsulates the IP packet into a MAC frame addressed to the destination host.

A packet addressed outside of this range, for this example, addressed to 192.168.12.3, cannot travel directly to the destination. Instead it must be sent to the default gateway for further routing to their ultimate destination. In this example, the default gateway uses the IP address 192.168.4.1, which is resolved into a MAC address with ARP in the usual way. The destination IP address remains 192.168.12.3, but the next-hop MAC address is that of the gateway, rather than of the ultimate destination.