DHCP

At my day job, we were tasked with creating a Windows NT 4.0
network from scratch with only minimal training on the operating
system. We were experts at working with OpenVMS and MacIntosh
systems, but none of us had ever seen Windows NT before. In those
days long ago we were very cocky, and very naive - how hard could
it be to set up a new TCP/IP network? After all, we had mastered
DECnet and Appletalk, could IP be any harder?

We soon learned the error of our ways - TCP/IP is far more complex
than we had originally believed. However, after some head
scratching and a few phone calls, we managed to get our network
up and running.

We didn't know any better, so we simply hard coded the TCP/IP
address into each workstation and server. In fact, we hard coded
everything, including the DNS and WINS server addresses, the
subnet and the gateway address.

For our purposes, this worked great for several years. We added
machines slowly and planned everything far in advance, so it was
no big deal to just add a new machine to the network. A few
simple edits to the network control panel was all that was needed,
and since our network was very static, we didn't have to visit
those setting very often at all.

As our company grew this scheme started to get more and more
awkward. Originally we had a nice, isolated, self-contained
network, but now we needed to get on the internet, we were adding
not only new workstations and servers at a furious rate, but we
had to deal with PDAs, handheld systems, standalone file servers
and hundreds of other computers.

To make matters even worse, where our network was very static,
now it was becoming dynamic. Computers would be added and removed
constantly - someone would plug his handheld into an ethernet
jack, get their email, unplug and be gone.

The static TCP/IP scheme that we had been using (a spreadsheet
with a list of machines and related addresses) was simply no
longer working. Fortunately, there was an answer - DHCP.

The acronym DHCP stands for "Dynamic Host Configuration Protocol",
and it means exactly what it says. Once we discovered this new
tool we realized we had found the solution to our problem - and
we kicked ourselves mentally for not reading up on this wonderful
tool long before.

To use DHCP is so straightforward that the only excuse for not
using it is lack of knowledge. You create a DHCP server -
depending upon the size of your network this can be added to an
existing server (the network traffic is not usually very high) or
you may need to use a dedicated system. Some people use the DHCP
server that comes with Windows NT or whatever operating system
they happen to be running. We found the best solution was to
purchase a "DHCP appliance" - a small computer intended to host
DHCP and only DHCP.

Once you've got your DHCP server installed, you use an interface
of some kind (often just any browser such as Internet Explorer)
to define your network parameters. These include the range of
available TCP/IP addresses, the gateway address, the addresses
(primary and secondary) of your DNS or name servers, and any of
dozens of other parameters.

Now comes the really cool part. From this point forward, any
machine on your network can, if told to do so, get all of the
TCP/IP information from this DHCP server. This means you no longer
need to enter and/or change any of this data. It's all handled for
you. Windows 2000 Professional systems even use DHCP by default,
which means new workstations practically work out of the box.

To make this all easy for home users as well, many hardware
firewalls include a DHCP server as part of the package. This
means if you get one of these firewalls (and it will tell you on
the box or instructions if it has a DHCP server built-in) you can
just plug computers in at home and not worry very much about
TCP/IP.

The bottom line is there is no reason not to use DHCP for your
workstations, laptops and handheld devices (it's not a good idea
in general to use it for servers). You can even use it at home if
you get the proper firewall.