The mystique surrounding cables is partly justified. A single intermittent connection in a cable can spawn troubleshooting efforts leading in many false directions. Always buy cables certified to conform to the Category 5 (known as CAT 5) standards of the EIA/TIA (Electronic Industries Association and Telecommunications Industry Association).

In large corporate networks, IP addressing is a job for experts. The need for network efficiency forces network administrators to consider ways to break the addresses down into subgroups aggregated according to traffic patterns and workgroup affiliation. Additionally, large networks contend with a limited supply of IP addresses.

Those planning smaller networks can choose from among two special blocks of IP addresses set aside for internal use. One block is 10. 0. 0. xxx and the other is 192.168.xxx.xxx (where you decide what numbers to use in the positions marked with an x). A device called a DHCP (Dynamic Host Configuration Protocol) server can assign addresses from these blocks as devices in your home or organization connect to the network. A service called network address translation (NAT), typically provided by your router or gateway, takes the multiple IP addresses within your network and presents an acceptable single IP address to the Internet. NAT offers some protection from Internet intruders because they can see only the single IP address presented to the Internet, but not the IP addresses within your network. Home and small office networks almost always use DHCP and NAT. Note that some devices, such as printers, need an assigned static IP address so that other systems on the network always know where to find these devices. There is no problem with combining dynamically assigned and static IP addresses on the same network.

You should also consider the security of your backup. If you use removable media, like tape or CD/RW, then periodically placing backup copies of your most important files in some other location is a good idea.

Network attached storage (NAS) devices come alive after you plug in two cables: one for power and one for the network connection. Immediately, all authorized users see another disk drive or storage location. These devices offer high capacity, high reliability, and ease of use.

At the LAN end, the VPN termination can reside in routers, dedicated VPN devices, or software running on special-function servers. The cost of VPN-equipped routers is dropping, but cost isn't everything. The lower-end devices can only handle a limited number of interactive sessions. (The actual capacity depends a great deal on the amount of traffic generated in each session.) As a rule of thumb, if you have more than a few dozen simultaneous sessions, you need a dedicated VPN device. Several vendors are now offering low-cost routers with VPN services for the small-office market.

Network administrators should also be aware that most VPNs do not allow split tunneling, which lets a client using the VPN access the Internet without having to go through the VPN. As long as the VPN session is active, all client requests for Internet services will go through the VPN tunnel to your network. Your network will provide all Internet access and services for the client. In effect, you will become the ISP for your VPN users. If a telecommuter activates the VPN, checks e-mail and corporate applications, then de-activate the client, there is little impact on traffic. However, if a person working off-site keeps the tunnel active and then engages in Web surfing, there will be a greater impact on the company's Internet traffic.

Wireless LANs are sometimes used to extend the reach of a wired network beyond the cable so that workers can roam within a building or even to fairly distant corners of, let's say, a campus. On a campus, for example, access points might appear every couple of hundred feet for complete coverage. In a small office, one access point might cover the entire facility. In a home, an Internet router or gateway might include a wireless access point to allow roaming connections and a switch for wired connections.