Many customers buy a router at Fry's or Best Buy to connect their internal network to the Internet, and then find that their network is slow or the server becomes unavailable. The correct configuration is to always use both the DHCP and DNS server built into your server operating system, and disable the DHCP server on the router.

In one network I saw, logging onto Windows XP took more than five minutes because the DNS server was misconfigured.

If this is such a dangerous feature, why do routers have it?

These features were designed for home networks without a regular server. In such a home setting, using the router's DHCP and DNS features actually makes sense and makes life much easier. It only becomes a problem in business networks with a central server.

The purpose of DNS

DNS translates names such as www.google.com into IP addresses that the computer understands. In a business network, you generally create additional internal domains, or zones, with names such as mycompany.local or mycompany.size. Note that these internal domains usually do not end with .com or .org - this avoids a conflict with domains on the Internet.

These internal zones are extremely important; in particular Microsoft Active Directory relies heavily on them. A router cannot know about these internal zones.

The purpose of NetBIOS broadcasts, and why you don't want them

Did you ever have problems making computers appear in your Network Neighborhood? Odds are that you were using NetBIOS broadcasts that were not working properly.

If you do not have a central server to keep track of all computers on your network, Windows needs to rely on a different mechanism to find other computers: broadcasts. Imagine that your network is a large room full of blindfolded people (instead of computers). Every few minutes, one of the people/computers would should "Hey, who all is here?" and all people/computers would respond "I am Joe" "I am Amy" "I am Accounting" and so on. Obviously, this is a very noisy and inefficient mechanism; when you have more than four or five computers, it begins to break down.

The purpose of WINS

WINS is very similar to DNS in that it keeps track of all computers in a central server. It is sometimes still used in Microsoft-based networks.

The purpose of DHCP

DHCP assigns IP addresses, DNS server settings, WINS server settings, and other configuration settings to each computer. In a server setting, it will usually also inform the DNS server about each new computer on the network.

A router-based DHCP server can never assign all the correct settings

Summary

Just say NO! The router can never know enough about the settings you need to assign, nor about the internal DNS zones. Do not enable the DHCP server in your router, rely on your server for all network management functions, and enjoy your worry-free network.