Back To Basics: Windows 2000 Rogue DHCP Server Detection?

Back To Basics: Windows 2000 Rogue DHCP Server Detection?

October 9, 2000

Thomas Shinder

Your question from last week about WINS Servers in Windows 2000 got me to thinking about our WINS configuration. My company has about 35,000 client computers distributed across ten physical locations. By last count, we have 55 WINS Servers on the network. We frequently run into problems with replication and WINS database corruption. Some people have mentioned that we might have too many WINS Servers and this is what is causing the problem. How many WINS Servers should we have on our network?


Microsoft says in a number of documents in TechNet that you should never implement more than 20 WINS Server without calling them. What they're trying to get at here is that if you need more than 20 WINS Servers, you may not be designing your WINS network optimally, and you should get some help.

WINS Servers are actually capable of servicing a large number of WINS clients. A single WINS Server can process over 5000 NetBIOS Name Query Requests per second and over 1000 NetBIOS Name Registrations per second. That's a lot. In fact, in the event that you suffer some kind of major power outage, and you find that 20,000 machines start up almost simultaneously and want to register themselves with a WINS Server, the WINS Server can handle this via Burst Mode Handling of registrations.

When a WINS Server is in Burst Mode, it will ACK a NetBIOS Name Registration immediately and give a short TTL for the registration. The WINS client gets this short TTL and will attempt to refresh its name registration a lot earlier than it would otherwise. Its important to note that the name is not registered in the WINS database at this time.

A good estimate on the number of WINS Servers you need is about one WINS for every 10,000 WINS clients. However, your network Topology is important when making these kind of assessments. You should have, ideally, one WINS Server and a Secondary WINS Server (for fault tolerance) on each side of a WAN link. Of course, smaller satellite offices that have a single segment and rarely need NetBIOS Name Resolution services for computers other than those on their local segment do not need a WINS Server, as they can be configured as m-node clients to optimize NetBIOS name resolution.