This summer we rebuilt our network, moving from a layer 2 10.x.x.x flat network to a layer 3 network with over 30 subnets and VLANs. We also simultaneously replaced our 2003 DC's with 2008R2 DCs. Since the change we are getting hundreds of errors on our servers like this one: Event 8003, bowser error: The master browser has received a server announcement from the computer MattLaptop that believes that it is the master browser for the domain on transport NetBT_Tcpip_{DBB64C40-5E00-4435-9E2C-13588043E022}. The master browser is stopping or an election is being forced. We have over 1000 computers on our network and there's no consistency as to which computer is the offender, thinking it's the master browser. Additionally we noticed that at times (but not consistently) it takes VERY long to populate the list of computers when a user goes to browse the network. Here's what we've tried thus far: - implementing a WINS server, add WINS IP to all DHCP scopes - changed WINS node type in DHCP to use P-mode (0x2) - decommissioned all 2003 DCs, now running with two 2008R2 DC's win AD 2003 domain & forest levels Has anyone ever had this problem? If so how did you resolve it? One consultant recommended blocking UDP ports 137 & 138 on my 3750 distribution switches (using Cisco helper to forward DHCP broadcasts back to DHCP). This is per MS articles kb190930 & kb135464. My reluctance in doing this is I've talked with network admins from other large enterprises with much more complicated networks and no one has ever had a problem with this. Thanks for any ideas!

There will be no consistency about which machine reports that it thinks it is the master browser. This is a symptom, not a cause. When a machine cannot obtain a browse list (because it cannot find a master browser), it assumes that browsing has failed. It then declares itself the master browser to force an election. That is how the system works. The machine which actually triggers the election is not the problem. Browsing is an NT legacy app, so it really has nothing to do with AD or DNS. Basically it relies on Netbios names and LAN broadcasts, and originally only worked in a single segment. To enable it to work across routers you need to have WINS and Netbios over TCP/IP, and you need all machines to register with WINS. WINS allows the master browsers to communicate directly (rather than through broadcasts) by converting names to IP addresses. First up, make sure that all of your servers have Netbios over TCP/IP enabled. If any of them are multihomed, make sure that only one interface has NBT enabled. Apart from that, debugging browser problems is still the same as it was in NT. The standard tool is browstat. The standard decription of browing is KB188001 and the standard troubleshooter is KB188305. Bill

Hi Matt, Have you also migrate the FSMO roles to new window server 2008 R2 host ? You might like to follow what bill mentioned that use Browsstat to check if the new domain server is master browser for this new domain. If not, please checked the IsDomainMaster registry value of the PDC and make sure it is true. For more information ,please take look the articles below: Common Questions About Browsing with Windows http://support.microsoft.com/kb/136712 8003 browsing errors with UDP forwarding http://support.microsoft.com/kb/135464 Thanks. Tiger Li TechNet Subscriber Support in forum If you have any feedback on our support, please contact tngfb@microsoft.comPlease remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

Hi Matt, If there is any update on this issue, please feel free to let us know. We are looking forward to your reply. Thanks. Tiger Li TechNet Subscriber Support in forum If you have any feedback on our support, please contact tngfb@microsoft.comPlease remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.