Can I install KMS on Server Core ?


Server Core seems to be the perfect candidate for installing KMS. Key Management Service mediates your Volume Licensing with Microsoft Activation Services and acts as the man-in-the-middle for the activation for all your KMS clients that comprise of Vista, Windows 7, Windows Server 2008 and R2. With Windows 7 and Windows Server 2008 R2, what you have in KMS is Volume Activation 2.0. In contrast with KMS, what you have is MAK that stands for multiple activation key. MAK is targeted for clients that stay off the network whereas KMS is designed for your internal clients. Following I have a simple overview design of how it works.


My Windows Server 2008 R2 Server Core has a very small footprint, it is a single processor/20gb hd/512mb ram machine. The first thing you need is the KMS Host key from your Microsoft Volume Licensing site or from your TAM.
The command to register the machine as the KMS host is slmgr /ipk <your key>


Once it is registered, you need to activate the host itself. Run slmgr -ato
You can check the status and brief description of the KMS host by running slmgr –dli


The verbose information is provided via slmgr –dlv


Once KMS is setup, it will register its SRV record in DNS. You can verify from your workstation if it has done so via,

nslookup -type=srv _vlmcs._tcp

From then on clients will automatically be reverted to your KMS host for activation but as hinted in the drawing above, starting with Windows 7 and 08 R2, the minimum threshold (activation attempts/requests) that are needed to fully activate the KMS host is 25 Vista/Windows 7 clients or 5 Server 2008 (R2). This number can comprise of virtual and physical loads, previously this was limited to physical systems only. The slmgr -dlv will show you the total requests received.
Note that the KMS is desgined to let you better manage your internal activation for compliance reason. Micrsoft does not go receive any internal information from between the KMS host and KMS client. KMS has you abide your EA Volume Licenseing, check the VL Product Groups shown in the diagram that are pertinent for your environment. I find the group B to be most commonly required.

Important note : Installing/configuring the KMS does not open up the pertinent firewall port (default port 1688). From running “slmgr -dli” you will notice that it says that the KMS is listening on port 1688 but the rule is not enabled so you may do so like this.

netsh advfirewall>FIREWALL add rule name=”KMS” dir=in action=allow protocol=tcp

For more information see this link.

Time Synchronization for Virtualized DCs


As usual a good conversation spurred on ActiveDir on a much discussed scenario of virtualizing your DCs while be varied of the known pitfalls. While virtualized DCs are fully supported on either competing virtualization solution by Microsoft, one known subject I would like to highlight here is the proper time synchronization. You must make sure that your PDCe gets its time from an external time source and other DCs follow the PDCe. All DCs (including PDCe) must not sync their time with the virtualization host, whether its VMware ESX or that of Hyper-V. It was discussed how by default the VMware’s VM settting does not have the time synchronization enabled by default, and my brief look at the Hyper-V’s VM suggested that it is. In any case, you must make sure that setting is disabled, thus VM does sync its time with its host.

VMware time setting from the VMware tools within the VM:


Or under the VM settings from VIC :


Hyper-V setting from the VM settings :


A great resource to refer to, to learn how to configure an authoritative time source for your DCs – see this KB

What is DNS Cache Locking in Windows Server 2008 R2 ?


One of the DNS improvements in Windows Server 2008 R2 is DNS Cache Locking in which if configured the cache entries are not allowed to be modified for the percentage of TTL.

Cache locking is a new security feature available with Windows Server® 2008 R2 that allows you to control whether or not information in the DNS cache can be overwritten. When a recursive DNS server responds to a query, it will cache the results obtained so that it can respond quickly if it receives another query requesting the same information. The period of time the DNS server will keep information in its cache is determined by the Time to Live (TTL) value for a resource record. Until the TTL period expires, information in the cache might be overwritten if updated information about that resource record is received. If an attacker successfully overwrites information in the cache, they might be able to redirect traffic on your network to a malicious site.

Cache locking is configured as a percent value. For example, if the cache locking value is set to 50, then the DNS server will not overwrite a cached entry for half of the duration of the TTL. By default, the cache locking percent value is 100. This means that cached entries will not be overwritten for the entire duration of the TTL. The cache locking value is stored in the CacheLockingPercent registry key. If the registry key is not present, then the DNS server will use the default cache locking value of 100.

You can configure the CacheLocking with DNSCMD utility from the command line (launched under elevated rights).

dnscmd /Config /CacheLockingPercent <percent>

You may also check the current percentage set for this setting with the /info switch of DNSCMD.


With above, the pertinent DWORD registry key is created under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\DNS\Parameters

However, in real world you push down this registry key via Group Policy Preferences to all your DNS servers. Values for the key are shown below.


PowerShell : How many users were created in an office since x number of days ?


A request came in from the Access Control team requesting that they be provided with the users that have been created in a particular office since last 90 days. As usual, PowerShell (with QAD cmdlets) has very simple one liners you can retrieve this information with.


You may also use this to export this data to a CSV file. Notice that when using the export-csv cmdlet you must choose the ‘select’ and define the attributes that should be exported. Format-Table (aliased above as FT) is used to display the information on the console.

GetQADUser-sizelimit 0 | where{$_.whencreated -gt (get-date).adddays(-90)}| select Name,WhenCreated,DN | Export-csv c:Users90days.csv

There is always a couple of ways to accomplish the same task with further fine tuning your query. As you can see that above query would grab all the users in the domain, going by their whenCreated attribute and present you the pertinent users.

You can define the OU to search with the –searchroot parameter.

Get-QADUser –Searchroot ‘’ | where{$_.whencreated -gt (get-date).adddays(-90)}

Alternatively, if you would to like find users account that have been modified since x number of days, you can try something like this.

Get-QADUser -LastChangedAfter (get-date).adddays(-7) -search $OU -sl 0 | ft name,whenchanged