So much for the hardware. It's time now to cover a little networking theory, starting with addressing. Networks these days use a protocol called TCP/IP (short for Transmission Control Protocol and Internet Protocol) that requires every networked PC, server and other device to be configured with a unique identifying number: its IP address. The address is typically 32 bits long, and expressed as a set of four decimal values between 0 and 255, separated by full stops.

For example, the PC l'm writing this article on has an IP address of 192.168.0.10 while the router that connects it to the internet (referred to as the default gateway) has an address of 192.168.0.1.

lP addresses can be manually assigned, and for devices such as routers and servers this is the best approach as you don't want their addresses to change. However, if you make a mistake you can end up with duplicate addresses, which isn't good, so for everything else it's better to assign addresses automatically using the Dynamic Host Configuration Protocol (DHCP).

DHCP hands out addresses from a preset range that avoids duplicates, and you can also use it to tell client PCs the address of the internet router. It's really useful, especially with a mobile notebook or PDA, as it lets you connect to different Wifi networks without having to manually change the gateway address every time.
On the downside you'll need a DHCP server, but most routers now come with one built in, so this isn't a major issue. The DHCP server will normally be turned on by default, so all you have to do is ensure your network PCs are configured to obtain their addresses automatically. Again, that's now the default when Windows network connections are created. If not, it's very easy to change.

For most home networks DHCP is a no-brainer, as it just works. Things can go wrong, though, for example if you have more than one DHCP server on the network. DHCP servers can be built into all kinds of devices, so if problems arise check if that's the cause and turn off any you don't need.