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Computer Browser Service: How It Works with SMB 1.0/CIFS File Sharing Support



On each network segment, a master browser is elected from the group of computers located on the segment that are running the browser service.The master browser is responsible for collecting host or server announcements, which are sent as datagrams every 12 minutes by each server on the network segment of the master browser. The master browser instructs the potential browsers for each network segment to become backup browsers. The backup browser on a given network segment provides a browse list to the client computers located in the same segment.


In a Windows NT domain structure, the primary domain controller (PDC) is always selected as the domain master browser. Only the PDC can be a domain master browser. If a PDC is not present, a domain master browser is not available and you are unable to obtain browse lists from workgroups other than the workgroup you are located in.Because the browser service is bound by broadcast segments and each master browser maintains its own separate list, there must be a way to merge these lists into a single domain-wide list. This functionality is provided by the domain master browser that is the PDC for the domain. This functionality is not required for network protocols other than Transmission Control Protocol/Internet Protocol (TCP/IP).




Computer Browser Service



On a given network segment, there is only one master browser. All domain controllers other than the PDC are designated as backup browsers. Additionally, one backup browser is allocated for every 32 computers on the network segment.In a workgroup configuration containing Windows NT Workstation-based computers, there is always one master browser. If there are at least two Windows NT Workstation-based computers in the workgroup, there is also one backup browser. For every 32 Windows NT Workstation-based computers in the workgroup, there is another backup browser.


If there is not a domain controller present on a given network segment, then an election process is started that chooses a master browser and backup browser from the computers on the segment using the following order of priority:Windows 2000 Server Windows 2000 Professional Microsoft Windows NT 4.0 Server Enterprise Edition Microsoft Windows NT 4.0 Server Microsoft Windows NT 4.0 Workstation Microsoft Windows 98 Microsoft Windows 95 Microsoft Windows for Workgroups 3.11


The PDC merges all the lists gathered by the master browsers on each segment across the WAN. Every 12 minutes, the master browser connects to the PDC to obtain the domain-wide list. The list is obtained by first issuing a NetServerEnum request with a flag of 0xFFFFFFFF. This request retrieves the complete list of servers within the domain. The master browser then issues the same request with a flag of 0x8000000, which requests all of the domain and workgroup names.To signal the PDC to retrieve the list collected by this master browser, the master browser sends the PDC a directed master announcement frame over User Datagram Protocol (UDP) port 138. This signals the PDC to immediately connect to the master browser and retrieve its list. This communication is also performed with two NetServerEnum requests. First, a NetServerEnum request with flag 0x40000000 is issued to request the local list of servers collected by the master browser. Then, a NetServerEnum request with flag 0xC0000000 is sent to retrieve the local workgroup announcement frames sent by the master browser of other domains or workgroups on its segment. Each backup browser on the segment issues a NetServerEnum request with flags of 0xFFFFFFFF and x80000000 at 12-minute intervals to obtain the complete list of servers, domains, and workgroup names.


Name resolution across the domain is critical for the distributed browsing model to operate. All computers across the WAN that are potential master browsers must be able to resolve the DomainName type entry for the PDC. After a potential master browser receives a positive response to the query for a PDC, the master browser must also be able to resolve the computer name type entry of the PDC. The PDC must be able to resolve the names of all computers that are potential master browsers in order to be able to connect to them. The PDC listens for directed master announcements from the master browsers on UDP portThis announcement triggers the PDC to resolve the computer name type of the master browser, and to request the browse list maintained by the master.Once a browse list is presented to a client computer, the client computer must resolve the NetBIOS name entry of any computer listed in order to view shared resources. Therefore, all client computers must be able to resolve the Internet Protocol (IP) address of all computers in the domain. In most networks configurations, this means that the distributed WINS infrastructure must be working properly.


Computer Browser Service is a feature of Microsoft Windows to get a list of computers and shared resources on a network and supplies this list to the computers on the network. If this service is stopped or disabled or not installed, this list will not be updated and any services or tools that explicitly depend on this service will not work.


The Computer Browser service is a legacy service that depends on SMBv1 protocol (SMBv1 client/server components). Microsoft publicly deprecated the SMBv1 (Server Message Block version 1) protocol in 2014.


As already mentioned, if the Computer Browser service is not installed or stopped, the services or tools which depend on this service will not work. The following listed tools and APIs will not work without this service.


As already mentioned, for security reasons, Microsoft is working hard to persuade users not to use SMB v1 (which includes the Computer Browser service). But if you really need it, you can enable it in a client machine by following the below steps.


Maintains an updated list of computers on the network and supplies this list to computers designated as browsers. If this service is stopped, this list will not be updated or maintained. If this service is disabled, any services that explicitly depend on it will fail to start.


Computer Browser is a Win32 service. In Windows 10 it is starting only if the user, an application or another service starts it. When the Computer Browser service is started, it is running as LocalSystem in a shared process of svchost.exe along with other services. If Computer Browser fails to start, the failure details are being recorded into Event Log. Then Windows 10 will start up and notify the user that the Browser service has failed to start due to the error.


3. Close the command window and restart the computer.The Browser service is using the browser.dll file that is located in the C:\Windows\System32 directory. If the file is removed or corrupted, read this article to restore its original version from Windows 10 installation media.


The Computer Browser service is running as LocalSystem in a shared process of svchost.exe. Other services might run in the same process. If Computer Browser fails to start, the error is logged. Windows 10 startup proceeds, but a message box is displayed informing you that the Browser service has failed to start.


Everything i have read says that in a domain environment, the presence of a dc doing the browser job means that you can disable the browser on workstations. In fact, i occasionally saw that some workstations were forcing master browser elections, so i set the computer browser service to start manually on every workstation i happened to work on. I just didn't have the guts to disable it outright as i know that if set to manual some processes will start it.


Then my laptops went out of office in groups of 2-5 and connected via ad-hoc network. They have a program that synchronizes files between them and depends on windows file sharing. Because they are all on the same domain and are using their domain credentials, security should not be an issue. Yet, sometimes computers connected on the ad-hoc, or by a portable wireless router, or directly connected on a little 4port hub still have difficulty in finding each other.


According to this http:/ Opens a new window/support.microsoft.com/kb/188001 Opens a new window I would say you assume correctly, you will need the service if you don't have an AD structure, and if you do have an AD structure the PDC is always the Master Browser and subsequent DCs backups to the master.


I have my default domain GPO that disables this service on all systems. Additionally, I leave it alone on the default domain controller GPO. All clients can see "browse" the network flawlessly. I initially had this service disabled on all systems until I got reports that the browse list was incomplete. Re-enabling on the DCs (the PDC is all that matters) immediately fixed this issue.


The browser service is a hold over from Wins and single lans without routers, but allows for bridges; but it's all pre active directory tied to dns stuff. We disable the browser service on our desktops and do it all through dns.


I always see those damn event log entries on workstations saying "PC X thinks it is the master browser and is forcing an election" but never really got round to looking into it so if you find that disabling this service gets rid of that and doesn't cause any negative effects then I'd be interested to hear about it :)


Please help! I can't connect to other computers on my network, and I think it is because a few of my services can't start/run. Started to happen after I installed a windows update. Not sure if it is related to a windows update or not. Ran Malware bytes and it didn't find anything. 2ff7e9595c


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