Browser Service Windows 2003 and port flooding

When I run a network sniffer i get several of the following errors

Source: (PC)
Destination: (Switch)
Protocol: Browser
Info: Domain/Workgroup announcement <my domain controller name>

Protocol: NBNS
info: name query, nb_illegal nescon(00)

Question: My domain controller is on a 192.203.x.x network
How does the 192.201.x.x  network know of the domain controllers existence

The PC whose address is has a second NIC which is on the 192.203.x.x network

Question 1: How do I stop my domain controller from broadcasting to other subnets that are physically separate (no VLAN's configured, but each network has its own switches with no routers to other switches)?

Question 2: If I have hardcoded ip addresses how can i stop my dns from broadcasting? Should I use WINS on top of DNS? There are 12 PC's connected to the domain controller. I want to stop browser elections and browsing? If browsing stops are there any negative effects?

I also have problems where computers added to the domain take longer to ping the domain controller then computers on the same subnet that aren't added to the domain.

I am using layer 2 switches
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Justin OwensITIL Problem ManagerCommented:
Is it UDP on  port 137?  If so, it is NETBIOS broadcasting.  NETBIOS broadcasting isn't required for AD to function in its native format.  You may experience problems if running legacy apps which utilize it and it is disabled.
adimitAuthor Commented:
forgive me but I am not sure of what you mean by UDP on port 137? I'm not an expert. The sniffer just told me that the brotocol is nbns and browser.
Justin OwensITIL Problem ManagerCommented:
NBNS is "NETBios Name Service".  If you disable NETBIOS on your server, it should quit producing that chatter.  UDP is a type of traffic.  Port 137 is the default port that NETBIOS uses to broadcast its signal.
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adimitAuthor Commented:
when you say server do you mean my domain controller?  My main concern is that a pc on one network knows about a domain controller on another. That's the problem i am trying to solve. I want to make sure that traffic for each physical lan doesn't go to another lan. no vlans are used. all networks are wired separately.
Justin OwensITIL Problem ManagerCommented:
You say they are wired seperately.  Are you meaning that there is no physical sharing of networking hardware of any of them?
If they share hardware and if you don't segment your network in VLAN, then your other subnets will be aware of it.  If you want to isolate traffice to a specific subnet, then you will need seperate VLANs for them.
adimitAuthor Commented:
most pc's have two network cards. each network card goes to a different switch. aren't the different subnets suppose to separate traffic?
adimitAuthor Commented:
I believe the information is correct, but I was hoping for an answer to my last question because I equate a subnet to a vlan to a broadcast domain and I am a little confused.  I also expect that switches on physically different networks are the equivalent of a vlan.
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