The following diagram shows the networking for general offices.

• The router like a hub provides Internet access for each PC on the LAN
• The router can be a DHCP server providing an IP address for each PC on the same LAN
(Eliminating the chance of assigning a duplicated IP address to a PC by a system administrator)
• Every PC on the LAN is possible to access the file server, shared printer, database or other applications, making client/server applications possible
• The firewall protects the LAN from an outside attack
• The firewall is also as an NAT. It translates private IP addresses of the PCs on the LAN to a public address (or addresses) so that the PCs or servers inside the LAN are not visible to the outside world
• The firewall can be configured to provide exposure of a particular server (such as a webserver) (in DMZ) on the LAN to the public - Internet