Posts Tagged ‘Active Directory’

Here is a quick reference you can use to determine which tools to use to help locate and resolve problems with your AD network.

Q: User unable to access network resources?

Is the network functioning at all? Can you view a list of networked systems or even access resources on other computers? If not, you have network connectivity problems. The troubleshooting tools you should start with include: Event Viewer, Ping, IPCONFIG, NLTEST, NetDiag and Network Monitor.

Q: User unable to locate resources by name?

Is name resolution functioning? Can you resolve NetBIOS or domain names into IP addresses using Windows Explorer or PING? If not, you have name resolution service problems. The troubleshooting tools you should start with include: Event Viewer, NSLOOKUP, NBTSTAT and DNSCMD.

Q: User unable to log in and obtain its roaming profile?

If not, your DC is having problems. The troubleshooting tools you should start with include: Event Viewer, DCDiag, DSASTAT and NTDSUTIL.

Q: User is unable to authenticate?

Can any client log on locally or remotely? If not, your DC is not authenticating properly. The troubleshooting tools you should start with include: Event Viewer and NetSetup.

Q: User unable to access resources as expected?

Can you access objects that you should be granted access to, and are you restricted from objects that you should not have access to? If not, then either the ACLs or DC is not functioning properly. The troubleshooting tools you should start with include: Event Viewer, DSACLS, NETDOM and SDCHECK.

Other Posts related to Active Directory:

https://ignitedsoul.com/2012/07/03/troubleshooting-tools-for-common-active-directory-problems/

https://ignitedsoul.com/2012/06/22/how-the-active-directory-communication-does-happens/

https://ignitedsoul.com/2012/01/23/what-is-the-sysvol-folder/

https://ignitedsoul.com/2012/01/23/replmon/

https://ignitedsoul.com/2011/10/12/how-to-restore-the-system-state-on-a-domain-controller-2/

https://ignitedsoul.com/2011/10/12/how-many-fsmo-roles/

https://ignitedsoul.com/2011/08/10/active-directory-roles/

https://ignitedsoul.com/2011/08/01/intrasite-and-intersite-replication/

https://ignitedsoul.com/2011/07/05/active-directory-intersite-replication/

https://ignitedsoul.com/2011/07/05/support-files-of-active-directory/

https://ignitedsoul.com/2011/03/04/active-directory-naming-and-ldap/

https://ignitedsoul.com/2011/01/05/review-of-active-directory-in-server-2008/

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Active Directory (AD) relies on several communications services to communicate with client computers and between domain controllers. The variety of communications protocols used reflects the complex nature both of AD and of the industry-standard protocols that AD implements, such as Kerberos and the Lightweight Directory Access Protocol (LDAP).

Understanding how AD communicates can be critical when you’re working with domain controllers or clients that are separated from domain controllers by firewalls or other port filtering devices (such as routers).

Basic Communications

AD needs only a few basic services to be available for normal operations:

User Datagram Protocol (UDP) port 88 is used for Kerberos authentication. Transmission Control Protocol (TCP) port 88 can also be used, although it’s less common.

  • TCP and UDP ports 135 are needed for remote procedure call (RPC) endpoint mapping. RPCs are used for a number of domain controller-to-domain controller and client-to domain controller operations. Unfortunately, not all communications take place over port 135, as I’ll discuss later.
  • TCP port 139 and UDP port 138 are needed for file replication between domain controllers. This port combination is the standard NetBIOS session service port set.
  • UDP port 389 handles LDAP queries and is used for normal domain controller operations.
  • TCP and UDP ports 445 are used for file replication and are the standard Windows files sharing ports.
  • TCP and UDP ports 464 are the Kerberos password change protocol ports.
  • TCP port 593 is used by the RPC over HTTP transport. Although you don’t technically need this port for normal operations, I’ll discuss later how this feature can make working with domain controllers through firewalls a bit easier.
  • TCP port 636 is for LDAP over Secure Sockets Layer (SSL), which is the default LDAP methodology for Windows Server 2003 and later.
  • TCP port 3268 and 3269 handle Global Catalog (GC) queries. Port 3269 handles secure queries. Any domain controller that needs access to a GC or that is acting as a GC server will use these ports.
  • TCP and UDP ports 53 are used to communicate with Domain Name System (DNS), which is a vital part of AD communications.

Generally, opening these ports between clients and domain controllers, or between domain controllers, will enable AD to function normally. One exception is RPC traffic.

 

The problems described in the symptoms section occur because of a lock on the Service Control Manager (SCM) database.  As a result of the lock, none of the services can access the SCM database to initialize their service start requests. To verify that a Windows computer is affected by the problem discussed in this article, run the following command from the command Prompt:

sc querylock

The output below would indicate that the SCM database is locked:

QueryServiceLockstatus – Success
IsLocked : True
LockOwner : .\NT Service Control Manager
LockDuration : 1090 (seconds since acquired)

There is no additional information in the Event Logs beyond those from the Service Control Manager indicating that Service startup requests have timed out. The underlying root cause is a deadlock between the Service Control Manager and HTTP.SYS.

Resolution

You can modify the behavior of HTTP.SYS to depend on another service being started first.  To do this, perform the following steps:

  1. Open Registry Editor
  2. Navigate to HKLM\SYSTEM\CurrentControlSet\Services\HTTP and create the following Multi-string value: DependOnService
  3. Double click the new DependOnService entry
  4. Type CRYPTSVC in the Value Data field and click OK.
  5. Reboot the server

NOTE: Please ensure that you make a backup of the registry / affected keys before making any changes to your system.

 

Issue: We had a System running Server 2008 and when it would boot it would hang with “Applying User Settings”.  When it would finally load, many of the services were not started.
Diagnosis: http://support.microsoft.com/kb/2004121 – This Microsoft Article explains the issue associated with the SCM database being locked:

sc querylock
The output below would indicate that the SCM database is locked:
QueryServiceLockstatus – Success
IsLocked : True
LockOwner : .\NT Service Control Manager
LockDuration : 1090 (seconds since acquired)

Resolution: You can modify the behavior of HTTP.SYS to depend on another service being started first.  To do this, perform the following steps:

  1. Open Registry Editor
  2. Navigate to HKLM\SYSTEM\CurrentControlSet\Services\HTTP and create the following Multi-string value: DependOnService
  3. Double click the new DependOnService entry
  4. Type CRYPTSVC in the Value Data field and click OK.
  5. Reboot the server

 

NOTE: Please ensure that you make a backup of the registry / affected keys before making any changes to your system.

DNS keeps track of Information in Zones. Essentially, a zone is a flat-file database for a particular domain, such as http://www.Google.com. The zone can contain different rexord types, all of which can be queried by clients:

> A : Which i a Host Address record – this resolves a single host name. suck as www, to an IP address.

> CNAME : or Alias – This resolves a name such as www to an actual host name, such as www1. think of it as a nickname for a computer -“www”, for example, is easier to remember and more standardized than a computer name like “w4salwin” which is what a Web Server’s real name might be.

> MX : or Mail Exchanger – This provides the name of the mail server for a Domain. Multiple MX records can be provided for fault tolerance or load balancing and a prioroty assigned to each. Clients, Such as sending mail servers, will attempt to contact the server in the MX record with the lowest-Numbered Priority.

> AAAA – This maps an IPv6 IP address to a host name.

> SRV: or Service – This provides the IP address of  one or more servers providing a particular service. AD uses SRV records to allow clients to locate Domain Controllers, among other things.

> SOA: or Start of Authority – This Special record indicates that the DNS Server hosting the zone is authoritative for the zone and is the primary source of name resolution for hosts within that domain.

All active directory data base security related information store in SYSVOL folder and it’s only created on NTFS partition.

In Microsoft Windows, the System Volume (Sysvol) is a shared directory that stores the server copy of the domain’s public files that must be shared for common access and replication throughout a domain. The term SYSVOL refers to a set of files and folders that reside on the local hard disk of each domain controller in a domain and that are replicated by the File Replication service (FRS). Network clients access the contents of the SYSVOL tree by using the NETLOGON and SYSVOL shared folders.

The Sysvol folder on a Windows domain controller is used to replicate file-based data among domain controllers. Because junctions are used within the Sysvol folder structure, Windows NT file system (NTFS) version 5.0 is required on domain controllers throughout a Windows distributed file system (DFS) forest.

ReplMon can do the following:

  • See when a replication partner fails.
  • Display changes that have not yet replicated from a given replication partner.
  • Trigger the Knowledge Consistency Checker (KCC) to recalculate the replication topology.
  • View the history of successful and failed replication changes for troubleshooting purposes.
  • Find all direct and transitive replication partners on the network.
  • View the properties of directory replication partners.
  • Display the metadata of an Active Directory object’s attributes.
  • Poll replication partners and generate individual histories of successful and failed replication events.
  • Create your own applications or scripts written in Microsoft Visual Basic Scripting Edition (VBScript) to extract specific data from Active Directory.
  • View a snapshot of the performance counters on the computer, and the registry configuration of the server.
  • Generate status reports that include direct and transitive replication partners, and detail a record of changes.
  • Display replication topology.
  • Force replication.
  • Display a list of the trust relationships maintained by the domain controller being monitored.

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You’ve probably noticed that Windows Server 2003 has a new feature that requests a shutdown reason each time you restart the server. This feature is called the Shutdown Event Tracker.

If you are working in a test environment, you might choose to disable this feature to avoid the hassle of typing in a reason each time you restart. To disable this feature, you can perform the following steps:

1. Click Start, click Run, and type gpedit.msc and press Enter.

2. Expand the Computer Configuration and then Administrative Templates objects. Click on the System object. In the right-hand pane you’ll see several settings appear.

3. Locate and double-click that Display Shutdown Event Tracker setting. The Display Shutdown Event Tracker Properties dialog box opens.

4. Click the Disabled radio button to disable the Shutdown Event Tracker. Click OK.

 

Close the Group Policy Editor console. Now when you shut down this server, you won’t be asked to enter a reason.