Troubleshooting the Browser Service

By Ace Fekay, , MCT, MVP, MCSE 2012/Cloud, MCITP EA, MCTS Windows 2008/R2, Exchange 2007 & 2010, Exchange 2010 Enterprise Administrator, MCSE 2003/2000, MCSA Messaging 2003
Microsoft Certified Trainer
Microsoft MVP: Directory Services
Active Directory, Exchange and Windows Infrastructure Engineer




Each subnet has it’s own master browser, and if you are using WINS, the master browser works together with the WINS service to enumerate an infrastructure wide browse list.

If not using WINS, it uses broadcasts, however, you’ll only see what’s on your own subnet, because NetBIOS broadcasts are more than likely blocked by routers, which is default, and many routers don’t allow NetBIOS broadcast across subnets to be enabled.

If you are in a multi-subnetted environment, and you want full browsing capabilities, to get around routers blocking NetBIOS broadcasts, it’s suggested to use WINS.

And the default WINS settings out-of-the-box, work fine, as long as you set up DHCP WINS options correctly. There is no need to adjust WINS’ registry parameters, otherwise you’ll find yourself trying to change registry entries on multiple servers and mis-keying something. Here’s more info on configuring WINS:

WINS – What Is It, How To Install It, WINS Replication Partner Design Guidelines, How to Configure DHCP Scopes For WINS Client Distribution, and more:

If you’ve just upgraded your PDC from Windows 2003 to Windows 2008 or Newer

The Computer Browser service on Windows 2008 and newer is disabled by default. If you want the PDC Emulator to do it’s job as the Master Browser and not have some workstation win the election (read below what that means), then I suggest to set it to Automatic and start it. Otherwise, browsing will not work properly and you’ll be chasing a ghost trying to figure out why. I usually just enable it on all of my DCs. More info in the following link:

NetBIOS browsing across subnets may fail after upgrading to Windows Server 2008

Preferably install at least one server OS on each subnet:

If there is a server OS, and it’s not multihomed, especially if a DC on the subnet and it’s not multihomed (multihoming a DC is a really bad idea), then it should win, unless there’s a problem with the machine itself, such as some sort of security setting in your antivirus blocking traffic, or firewall blocking traffic on it.

And as mentioned, if you just upgraded the PDC emulator to 2008 or newer, set the Computer Browser service to Automatic and start it.

If you find workstations are becoming masters, that means there are no server operating systems on those subnets, in such cases, the workstation will win Master Browser election.

And I realize in many large infrastructures, it would be nearly impossible to put a server operating system on each subnet. However, as long as there is a desktop using the latest client operating system that is always up and running 24/7, that will do the trick.

If a newer client OS were to be introduced, then it would start a master browser election, and win the election (OS version and server role is a factor in the election process). And any machine that someone clicks on Network Neighborhood or clicks a Browse button somewhere, would invoke an election, but if a desktop is running on the subnet 24/7, it will win the election, since it’s already up and running.

If you don’t want any other client machine to win the election and were to opt for only that one machine, you can set a registry entry using a GPO to disable participating in the browse list for all the machines in the subnet other than the client machine you chose to keep up and running 24/7:

Set the client machine of your choosing to:
Emulator MaintainServerList=Yes, IsDomainMaster=True

All other clients on the subnet, set it to:

I’m not saying this is a perfect solution, but it’s something to consider. Otherwise, if no specific machine is up and running 24/7 on any given subnet, the browse list will be rebuilt each time everyone shuts down, then brings their machines up in the morning, and the cycle starts from scratch to rebuild the list of machines on that subnet.


Third Party Devices Participating in the Browser Service

I would like to point out that if you have any 3rd party devices, such as a Seagate BlackArmor NAS, it will jump in on the election process and may win, which in case will snafu your browse list. I had one of those devices at a customer site last year causing numerous problems with the browse list, which in turned snowballed to cause problems with Symantec BackupExec, and other services that rely on browsing.

After some troubleshooting, I found that the BlackArmor NAS was consistently winning the election causing the problems. I couldn’t find anything specific on how to disable browser service participation on the device. It has the latest firmware. I contacted Seagate, and they said they couldn’t help me to disable the device’s ability to participate in the Browser Service.

I finally moved it on to its own VLAN so it can be king of itself on that subnet, so to speak. I gave it it’s own island. Smile


Browse List Propagation:

We have to keep in mind with troubleshooting the browser service, there is a time period you have to wait for the list to fully enumerate and become available on the master. A good example is when a server is shut off on a segment, and the workstations kick in, or the server is rebooted, wins the election, and begins a new cycle to enumerate the browse list from WINS and/or broadcasts. This can take a minimal of 12 minutes, upwards to the 48-minute full propagation cycle in a multiple-segment domain environment.


When to Troubleshoot

Below are the generic troubleshooting steps I used to troubleshoot the browser service that helped me find out the BlackArmor device was the culprit.

If you are seeing problems with the browser service, such as computers disappearing from the browse list, whether the cause is a third party device, Unix/Linux machine running Samba, or simply based on the infrastructure’s design, it might be a good idea to start troubleshooting to find the culprit.


Prepare to Troubleshoot:

  • Make sure the Computer Browser service is Started. Make sure NetBIOS is enabled on al machines.
  • On Windows 2003 and 2000, install the Support Tools (from the Windows CDROM) in order to have the “browstat” utility available.
  • With Windows 2008 and newer, the utility is already installed as part of the operating system files.
  • If there are any antivirus software, third party firewalls, or firewall rules between locations blocking WINS traffic (TCP 42), it could block browser traffic, too. This of course, assumes the Computer browser service is running.


Firewall blocks – Test it with PortQry

You can use the Portqry.exe utility to test if the Browser, SMB, WINS and the ephemeral (service response) ports are permitted.

  • Browser: UDP 137/138, TCP 139
  • SMB: TCP 445
  • WINS: TCP 42
  • Ephemeral (Service Response Ports): Varies depending on OS:
    • Windows 2000/2003/XP: TCP/UDP 1024-5000
    • Windows 2008/Vista and newer: TCP/UDP 49152-65535

Description of the Portqry.exe command-line utility

Active Directory Firewall Ports – Let’s Try To Make This Simple 


Multihomed DCs:

And if you have any multihomed DCs, among numerous other problems, that is a major cause of browser problems. Multhoming DCs is not recommended for multiple reasons, including a “Multihomed Browser” scenario. I suggest to disable one of the interfaces.

More info regarding multihoming DCs and why not to do it:

Multihomed DCs (with more than one unteamed NIC or multiple IPs) with DNS, RRAS, iSCSI, and/or PPPoE adapters – A multihomed DC is not a recommended configuration, however there are ways to configure such a DC to work properly.


Troubleshooting Steps:

Run a browstat status to see who the browse master is for the segment. If it’s not the PDC Emulator, and some other device won the election, that can cause a problem.

To check current status of the browse service on the domain, run:
browstat status

You should get a response similar to:
Browsing is active on domain.
Master browser name is: <serverName>

Note, the machine that is the current master browser will either be, depending if the machine type exists on the segment: the PDC Emulator, a replica DC on the segment, a member server, joined workstation, or workgroup member, Unix or Linux with SAMBA, etc.

If you find a device is winning the election, then we need to disable that ability in the device. If there are no features for that, contact their support department, or put the device behind it’s own subnet or VLAN to prevent it from winning the election on the production network.

To find the current browse master on a segment, you’ll have to find the TransportID:
First run:

browstat getmaster \device\netbt_el59x1 <domainname>

It will error out because the “netbt_el59x1” probably doesn’t exist, and will respond with the transports currently bound to the browser. Copy and paste the transport that does show up into your next command:

browstat getmaster \Device\NetBT_Tcpip_{C2055954-4F86-446F-ACBA-E00BE731C3FB} <domainname>

Force an election by running:
browstat elect \device\netbt_ieepro1 <domainname>

Then check the event logs to see which machine won the election. If it’s a device, such as I’ve found that Linux/Unix with SAMBA, or devices such as a Seagate NAS, may win the election and cause browsing havoc within an environment and get that familiar, but unwanting “Access Denied” when trying to browse.


Master Browser Election Process

I know, most of you probably wondered what the order of who would be the winner during a Master Browser election. The winner of a browse master election process is based on operating system version and role. It’s also based on each subnet.

So if a Windows XP client is on a subnet by itself, then yes, it may become an MB if nothing else beats it.

And if a Windows Server 2008 R2 DC is on subnet and on subnet there are only a bunch of Windows XP and 2000 computers, then the XP will win.

If the DC is multihomed, then that will definitely throw a wrench into it. Do NOT multihome your DC. Really, believe me, you don’t want to do it.

The following list shows the order of precedence of which operating system will win. And keep in mind, it’s subnet specific.

1. DC – PDC Emulator (no matter what OS)
2. DC – Non-PDC Emulator (no matter what OS)
3. Windows Server 2012
4. Windows 8
5. Windows Server 2008 R2
6. Windows 7
7. Windows Server 2008
8. Windows Vista
9. Windows Server 2003 R2
10. Windows Server 2003
11. Windows XP
12. Windows Server 2000
13. Windows 2000 Pro
14. Windows NT 4.0
15. Windows ME
16. Windows 98
17. Windows 95
18. Windows for Workgroups 3.11
19. Windows 3.1 with NDIS
20. DOS



Troubleshooting the Microsoft Browser Services:

Browser Elections 

Description of the Microsoft Computer Browser Service



Updated 10/18/2014

I hope this helps! I’m sure I may have missed something. Comments and suggestions are welcomed.

Ace Fekay
MVP, MCT, MCSE 2012, MCITP EA & MCTS Windows 2008/R2, Exchange 2013, 2010 EA & 2007, MCSE & MCSA 2003/2000, MCSA Messaging 2003
Microsoft Certified Trainer
Microsoft MVP – Directory Services

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Active Directory FSMO Roles Explained

Original Publication 1/16/2011
Updated 11/20/2014
by Ace Fekay

Ace here again. I’ve updated this blog to just clean it up a bit, but as for the technical information about FSMOs, not much as changed. If you see anything that you feel is inaccurate, by all means please contact me.


This blog contains some quoted material from the Microsoft Official Curriculum (MOC) 6425B Course

Course 6425C: Configuring and Troubleshooting Windows Server 2008 R2 Active Directory Domain Services

If interested in taking this course, please see the following link to find a training center near you:

Find Microsoft Training

Key Points

In any replicated database, some changes must be performed by one and only one replica because they are impractical to perform in a multimaster fashion.

Active Directory is no exception. A limited number of operations are not permitted to
occur at different places at the same time and must be the responsibility of only
one domain controller in a domain or forest. These operations, and the domain
controllers that perform them, are referred to by a variety of terms:

• Operations masters
• Operations master roles
• Single master roles
• Operations tokens
• Flexible single master operations (FSMOs)

Regardless of the term used, the idea is the same. One domain controller performs
a function, and while it does, no other domain controller performs that function.

All Active Directory domain controllers are capable of performing single master
operations. The domain controller that actually performs a single master operation is the
domain controller that currently holds the operation’s token, or the “role holder.”.

An operation token, and thus the role, can be transferred easily to another domain
controller without a reboot.

To reduce the risk of single points of failure, the operations tokens can be
distributed among multiple DCs.

AD DS contains five operations master roles. Two roles are performed for the
entire forest, and two roles are performed by three roles for each domain.

Forest Roles (two roles):

  • Domain naming
  • Schema

Domain Roles (three roles):

  • Relative identifier (RID)
  • Infrastructure
  • PDC Emulator

In a forest with a single domain, there are, therefore, five operations masters. In a forest with two domains, there are eight operations masters because the three domain master roles are implemented separately in each of the two domains.

Forest-Wide Operations Master Roles

The schema master and the domain naming master must be unique in the forest.
Each role is performed by only one domain controller in the entire forest.

Domain Naming Master Role:

The domain naming role is used when adding or removing domains in the forest. When you add or remove a domain, the domain naming master must beaccessible, or the operation will fail.

Schema Master Role:

The domain controller holding the schema master role is responsible for making any changes to the forest’s schema. All other DCs hold read-only replicas of the schema. If you want to modify the schema or install an application that modifies the schema, it is recommended you do so on the domain controller holding the schema master role. Otherwise, changes you request must be sent to the schema master to be written into the schema.

Domain-Wide Operations Master Roles

Each domain maintains three single master operations: RID, Infrastructure, and PDC Emulator. Each role is performed by only one domain controller in the domain.

RID Master Role

The RID master plays an integral part in the generation of security identifiers
(SIDs) for security principals such as users, groups, and computers. The SID of a
security principal must be unique. Because any domain controller can create
accounts, and therefore, SIDs, a mechanism is necessary to ensure that the SIDs
generated by a DC are unique. Active Directory domain controllers generate SIDs
by assigning a unique RID to the domain SID. The RID master for the domain
allocates pools of unique RIDs to each domain controller in the domain. Thus,
each domain controller can be confident that the SIDs it generates are unique.


The RID master role is like DHCP for SIDs. If you are familiar with the concept that
you allocate a scope of IP addresses for the Dynamic Host Configuration Protocol (DHCP) server to assign to clients, you can draw a parallel to the RID master, which allocates pools of RIDs to domain controllers for the creation of SIDs.

Infrastructure Master Role

In a multidomain environment, it’s common for an object to reference objects in other domains. For example, a group can include members from another domain.

Its multivalued member attribute contains the distinguished names of each
member. If the member in the other domain is moved or renamed, the infrastructure master of the group’s domain updates the group’s member attribute accordingly.

Note: The infrastructure master. You can think of the infrastructure master as a tracking device for group members from other domains. When those members are renamed or moved in the other domain, the infrastructure master identifies the change and makes appropriate changes to group memberships so that the memberships are kept up to date.

Also note: This role only pertains in a multi-domain forest. The infrastructure master if running on the same DC as a GC, will conflict and cause the infrastructure master role to fail its intended purpose. One way to eliminate any issues with the Infrastructure Master Role & GC conflict is to simply make all DCs a GC. More info on this can be found in the following link:

Global Catalog and FSMO Infrastructure Master Relationship

PDC Emulator Role

The PDC Emulator role performs multiple, crucial functions for a domain:

• Emulates a Primary Domain Controller (PDC) for backward compatibility
In the days of Windows NT® 4.0 domains, only the PDC could make changes
to the directory. Previous tools, utilities, and clients written to support
Windows NT 4.0 are unaware that all Active Directory domain controllers can
write to the directory, so such tools request a connection to the PDC. The
domain controller with the PDC emulator role registers itself as a PDC so that
down-level applications can locate a writable domain controller. Such
applications are less common now that Active Directory is nearly 10 years old,
and if your enterprise includes such applications, work to upgrade them for
full Active Directory compatibility.

• Participates in special password update handling for the domain
When a user’s password is reset or changed, the domain controller that makes
the change replicates the change immediately to the PDC emulator. This
special replication ensures that the domain controllers know about the new
password as quickly as possible. If a user attempts to log on immediately after
changing passwords, the domain controller responding to the user’s logon
request might not know about the new password. Before it rejects the logon
attempt, that domain controller forwards the authentication request to a PDC
emulator, which verifies that the new password is correct and instructs the
domain controller to accept the logon request. This function means that any
time a user enters an incorrect password, the authentication is forwarded to
the PDC emulator for a second opinion. The PDC emulator, therefore, should
be highly accessible to all clients in the domain. It should be a well-connected,
high-performance DC.

• Manages Group Policy updates within a domain
If a Group Policy object (GPO) is modified on two DCs at approximately the
same time, there could be conflicts between the two versions that could not be
reconciled as the GPO replicates. To avoid this situation, the PDC emulator
acts as the focal point for all Group Policy changes. When you open a GPO in
the Group Policy Management Editor (GPME), the GPME binds to the domain
controller performing the PDC emulator role. Therefore, all changes to GPOs
are made on the PDC emulator by default.

• Provides a master time source for the domain
Active Directory, Kerberos, File Replication Service (FRS), and DFS-R each rely
on timestamps, so synchronizing the time across all systems in a domain is
crucial. The PDC emulator in the forest root domain is the time master for the
entire forest, by default. The PDC emulator in each domain synchronizes its
time with the forest root PDC emulator. Other domain controllers in the
domain synchronize their clocks against that domain’s PDC emulator. All
other domain members synchronize their time with their preferred domain
controller. This hierarchical structure of time synchronization, all implemented
through the Win32Time service, ensures consistency of time. Universal
Coordinated Time (UTC) is synchronized, and the time displayed to users is
adjusted based on the time zone setting of the computer.

Note: Change the time service only one way. It is highly recommended to allow Windows to maintain its native, default time synchronization mechanisms. The only change you should make is to configure the PDC emulator of the forest root domain to synchronize with an extra time source. If you do not specify a time source for the PDC emulator, the System event log will contain errors reminding you to do so. See the following link and the articles it refers to, for more information.

Configure the Windows Time service on the PDC emulator in the Forest Root Domain

Configuring the Windows Time Service – A step by step with a Contingency Plan – This is a procedure I put together for an enterprise.

Configuring the Windows Time Service for Windows Server, explanation of the time service hierarchy, and more

Acts as the domain master browser
When you open Network in Windows, you see a list of workgroups and
domains, and when you open a workgroup or domain, you see a list of
computers. These two lists, called browse lists, are created by the Browser
service. In each network segment, a master browser creates the browse list: the
lists of workgroups, domains, and servers in that segment. The domain master
browser serves to merge the lists of each master browser so that browse clients
can retrieve a comprehensive browse list.

What happens when a FSMO Role Fails

PDC Emulator failure

The PDC Emulator is the operations master that will have the most immediate
impact on normal operations and on users if it becomes unavailable. Fortunately,
the PDC Emulator role can be seized to another domain controller and then
transferred back to the original role holder when the system comes back online.

Infrastructure master failure

A failure of the infrastructure master will be noticeable to administrators but not to users. Because the master is responsible for updating the names of group members from other domains, it can appear as if group membership is incorrect although, as mentioned earlier in this lesson, membership is not actually affected. You can seize the infrastructure master role to another domain controller and then transfer it back to the previous role holder when that system comes online.

RID master failure

A failed RID master will eventually prevent domain controllers from creating new
SIDs and, therefore, will prevent you from creating new accounts for users, groups,
or computers. However, domain controllers receive a sizable pool of RIDs from the
RID master, so unless you are generating numerous new accounts, you can often
go for some time without the RID master online while it is being repaired. Seizing
this role to another domain controller is a significant action. After the RID master
role has been seized, the domain controller that had been performing the role
cannot be brought back online.

Schema master failure

The schema master role is necessary only when schema modifications are being
made, either directly by an administrator or by installing an Active Directory
integrated application that changes the schema. At other times, the role is not
necessary. It can remain offline indefinitely until schema changes are necessary.
Seizing this role to another domain controller is a significant action. After the
schema master role has been seized, the domain controller that had been
performing the role cannot be brought back online.

Domain naming master failure

The domain naming master role is necessary only when you add a domain to the
forest or remove a domain from a forest. Until such changes are required to your
domain infrastructure, the domain naming master role can remain offline for an
indefinite period of time. Seizing this role to another domain controller is a
significant action. After the domain naming master role has been seized, the
domain controller that had been performing the role cannot be brought back

Recovering from FSMO Role Failures

There are a number of steps that must be performed if any of the FSMO roles fail, and keep in mind, it’s not just based
on the FSMO role failure itself, rather you must also take into account the DC, too, because it usually means the DC itself
has failed, therefore the DC failure must be addressed.

If a DC fails, then you must address the DC failure as a whole, and not just the FSMO roles. This is because the DC’s account is referenced in the AD database by other DCs, and it expects it to be there to contribute and work with replication, among other AD functions. Therefore you must clean out the DC’s reference from the AD database, which also includes seizing the roles it held to other DCs.

This also includes the services a specific FSMO role held, such as the Time Service. This service runs on the PDC Emulator and must be moved to the new PDC Emulator you are seizing the role to.

For more information, with a complete and specific step by step, including any services the DC held which was FSMO role specific, please see the following article for more information:

Complete Step by Step to Remove an Orphaned Domain controller

Monitoring DCs for failures

Microsoft Monitoring Products

There are a number of tools to monitor your domain controllers from native Windows event logs, to using SCOM.

System Center Operations Manager 2007 (SCOM) – Platform MonitoringOct 6, 2010 … Take advantage of System Center Operations Manager 2007 for cross-platform monitoring, beta software and management packs.

To learn how to use SCOM, Microsoft has a specific course just for this product. For more information on the course, please see:

Microsoft Official Curriculum Course 50028B:
Installing and Configuring System Center Operations Manager 2007

Third Party Monitoring Tools

There are also numerous third party monitoring utilities available such as the following list:

Quest – Windows Management Solutions – Trust the Experts for Simplified Windows Management

Network Monitor Software and Windows Development ToolsNetwork Monitor Tool site – Network Monitoring Tools for Windows, Linux, Unix and Novell.

NetVision Audit for Active Directory – Monitoring Active Directory – Active Directory Reports – Easy Audit Reporting and Real-Time Monitoring

Windows Monitoring, Windows Server Monitoring, Windows Application …Download Windows monitoring tool for Windows server monitoring, IIS Server, . … Monitor Windows CPU, disk, process monitoring, memory and ensure high …

Windows Server Monitoring and Windows Event Log Management SoftwareDevelopers of Windows administration tools that monitor in real-time system performance, security logs, and event logs, and send automated, user-defined …

Nagios Core – Monitoring Windows Machines:

Network Management Software | Server Monitoring | WhatsUp GoldWhatsUp Gold is an award-winning network monitoring software, managing over 100000 networks worldwide. Download trials & free tools now!

Comments, suggestions and corrections are welcomed!



I hope this helps!

Original Publication Date: 11/1/2011
Updated 11/4/2014

Ace Fekay
MVP, MCT, MCSE 2012, MCITP EA & MCTS Windows 2008/R2, Exchange 2013, 2010 EA & 2007, MCSE & MCSA 2003/2000, MCSA Messaging 2003
Microsoft Certified Trainer
Microsoft MVP – Directory Services

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