Microsoft AZ-140 Exam Guide – Azure Virtual Desktop Specialism – How to pass for (almost) free!

After finishing my most recent contract I took some time off to do some projects on my house and take a well earned break after 1 1/2 years with no let up. Inevitably after a few days I started feeling restless and having had one eye on AVD over the last 18 months (but no hands on experience) I wanted to get to grips with the technology and understand how it works, but did not expect I could pass a specialism exam as quickly as I did, so I wanted to share the steps I took with you so you can also benefit if you’re keen to learn about AVD without having to waste hours watching lame tutorials or reading over priced textbooks.

So, with ZERO prior AVD knowledge and very little general Azure experience, below details my approach to passing the AZ-140 certification, which took me around 2-3 weeks at (almost) ZERO cost and sitting the exam remotely (home proctored). I hope it helps you achieve the certification and good luck!

Exam Format

The AZ-140 exam is around 50-55 questions of which 15-20 of these are in a case-study style. Note that the exam is periodically updated to cover new technologies or developments to the AVD platform and you can expect the exam to include around 5 or 6 questions that are under review by Microsoft. You won’t know which questions these are (and they do count towards your final score), and you will be requested to provided feedback on them once your exam has been submitted.

Getting started…

I usually do a thorough high level skim-read of the main technologies that are referenced in the exam blueprint. Microsoft have an AVD learning course that covers the basics, do this and then look through the Microsoft Azure Virtual Desktop Documentation – don’t spend more than a day discovering and note taking because the next steps will alleviate any concerns or knowledge gaps you may perceive yourself as having…

Getting hands on experience with Azure Virtual Desktop: Register for Office 365 Premium Trial and Azure $200 free credits

Once you’ve given yourself a primer in the high level elements of an AVD environment you can now get hands on with AVD and (with bias) the best way to do this is to follow the Azure Academy AZ-140 study guide series on YouTube. This is literally the only resource I used for practicing the hands-on configuration and it will school you from AVD zero-to-hero in a few days. Before starting the series you will need to get a free 30-day trial of Office 365 Business Premium and register for an Azure account. The O365 trial is required in order to login to the AVD session hosts that you will build during the Azure Academy series (you must have a license in order to use the service). You should register for Office 365 Business Premium first and then register your Azure subscription using the same credentials. Bear in mind the 30-day clock is ticking once you have registered, so you should commit to study from this point on.

Register for Office 365 Business Premium trial here

Register for Azure here

Azure Academy AZ-140 YouTube Series

Dean Cefola’s Azure Academy AZ-140 Study Guide series is broken into 2 halves – videos 1-10 deal with planning for an AVD environment and cover things like understanding the preferred technologies for AVD and decision making for DR/failover, knowing what components are used in a typical setup and how to connect your on-prem services to AVD – it’s all tutorial based with no technical work. Video’s 11-20 are 100% hands on and will take you through the technical implementation of the ‘What The Hack’ pre-defined, design of the AVD environment (below).

The beauty of the series is that he covers every aspect of the exam using a mix of manual , ARM templates, Powershell and Azure CLI to build out 3-region AVD setup complete with DR, backup and an optional VPN so you can connect into your multi-session desktop hosts and test the service. You will learn everything you need to pass the certification, but also get clearly communicated explanations of all the components used in AVD with no technical guff and zero ego. Dean is also responsive to comments so you can get help when needed and simply put – this series will leave you feeling confident in how to setup an AVD environment and you will learn a ton whilst doing it, the entire What The Hack environment costs around £15-20 per day when it’s powered on and deployed, so you can spend a week or two tweaking and practicing without running out of free Azure credit. Just remember to switch off your VM’s when you’re not studying to ensure you don’t burn through your azure credits.

Final Prep: How Microsoft Test and Measure Up

When you book the exam you will have the opportunity to add MeasureUp AZ-140 Practice Test at a 50% discounted price to your exam booking – I would recommend doing this as it’s cheap and to this point you’ve not spent a penny and have no idea of the technical level of experience the exam questions are targeted at. I spent a couple of days working through the practice test, referencing the aforementioned KB articles for particular services, understanding the common misconfigurations in an AVD environment and ironing out the steps to take for configuring various AVD elements.

Microsoft love to write questions that are formulated from their knowledgebase articles. Whilst you are revising and re-configuring parts of the ‘What the Hack’ environment, make sure you reference the Microsoft KB’s and take notice of the order of the steps that the KB’s follow to configure a given component. For example, let’s take enabling authentication for an azure file shares – this is a question that will be guaranteed to appear on the exam and you should know the steps as detailed in the KB here – I emphasise this not because the Azure Academy misses steps, but the video series is relatively fast paced and it’s easy to overlook what the actual configuration steps are, particularly when Dean is providing you with the various scripts, templates or options to select, so my advice: avoid having a false sense of confidence and read the adjoining KB’s!

Good luck and thanks for reading!

I passed with a score of 920 and, for once, actually enjoyed every part of the study process – I hope you found this post useful, get out there and get learning!

VMware VCAP7-DTM 2021 Study guide and exam experience…

There’s not much information online to assist if you’re studying the VMware DTM track – last year I wrote a guide for studying VCP-DTM and having recently passed the VCAP-DTM Deploy I am sharing my experience below to help you prepare. You’ve probably already discovered Patrick Messenger’s VCAP-DTM Deploy Study Guide which is full of useful information, read on for my thoughts.

What is the VCAP Deploy exam like vs VCP?

VCAP Deploy is 100% hands on technical lab based exam. Unlike VCP, there are no theory or multiple choice questions. You are presented with a VMware HOL virtual lab which is very, very close reflection of this: HOL-2151-01-DWS – VMware Horizon – Getting Started with App and Desktop Virtualization and contains numerous mis-configurations within the Horizon stack (think connection servers, master images, AD/GPMC, pools, farms etc). You have 205 mins (3:25hr) to answer 28 questions. This may seem like a lot of time, and if you’re at VCAP level you’re probably a proficient engineer who can type fast and work quickly in vSphere but don’t be fooled! I have around 7 years experience with Horizon and ran out of time on the first attempt. The main ‘lag’ is getting used to the lab interface. Each question has a number of advisory comments which tell you what service or appliance you’ll need to log into in order to fix the issue (which I felt was generous!) as well as the required credentials – so in this respect there is some guidance as to where your focus will need to be. In most cases there are a list of requirements (which helps a lot) and limitations around what actions you should or shouldn’t do in order to complete the question – for example ‘Do not enable provisioning’ or ‘Use the default options unless specified’ and this helps provide scope. As you’d expect there’s a handful of easy softball questions ~25% at the beginning and towards the end of the exam, and the remaining ~75% are more involved and will require multiple troubleshooting steps to fix. I would strongly recommend you spend the first 20-30 mins of the exam skipping all the lengthy questions and cover the single-task questions. However, some questions are subjective and will require that you really think about what the ‘best practice’ is e.g. tune an instant clone image for a given use-case.

How to Prepare: My approach…

vMug, HOL, home labs and first attempts…

Unless your employer is covering your exam fees or training ,you’ll be forking out the best part of £400 to sit the exam – the VAT bites at checkout. I suggest buying a vMug advantage membership for $200 (sit on the vMug website for 10 mins and you’ll get a 10% discount popup appearing) – then use the 2x VCAP vouchers @ 20% discount. I think I’ve only ever passed 1 technical exam (no, not ITIL v3 Foundation) on the first take (CCNA Part Deux!) and if you’re half smart ‘you know how much you don’t know…’ or something like that – anyway, with this in mind I sat the VCAP (no revision) to dip my toes and test the water. I spend 8 hours a day doing work in Horizon/ESXi so I felt fairly confident I would achieve an acceptable score for a first try – I failed with a score of 220 – but the experience was hugely valuable and I didn’t really expect to pass first time as I know some of the topics covered features I’ve not touched for a few years (and thus, got rusty with) and in particular vIDM – I’ve never used Workspace ONE.

Prior to the first attempt I had considered forking out £1k on buying server equipment to build a nested home lab environment to study for this – I would recommend doing this if you’ve only got a few years experience with Horizon and perhaps haven’t ever setup an environment from scratch – it’s hugely valuable and will prove useful if you’re working on a VCP (DTM or DVC). However, for VCAP I don’t think this is really necessary – the money is better spent sitting the exam, particularly because the aforementioned HOL provides just about all of the functionality you need to get up to speed on the blueprint. All of the tech tested in the exam is available in the HOL and thankfully you’ll be using all the latest Horizon 8 features in the HOL, but be aware – the exam tests Horizon 7.X so you’re dealing with 7.10-7.13.

Another benefit to forking out for a first attempt is to steer your learning so you understand what depth to study the blueprint at – I tend to over think how much I need to know for technical certifications, and frankly, it can be detrimental to your life energy if you’re wasting time boring yourself digesting KB’s about edge-case configuration problems that appear as frequently as Prince Andrew – it’s highly unlikely these issues (inc Prince Andrew) will be covered on the test. I generally resign myself to the mentality VMware are going to shaft me for exam fee’s but ultimately having the cert will land me good roles as noble and honest recruiters look through the VMware certified professionals on LinkedIn. With this in mind, I started working toward the second and final attempt…

Exam blueprint

The blueprint is nice to look at – why? Because there’s f*** loads of topics that are not included in the Deploy exam 🙂 It is quite encouraging to see (what I consider) a short list of topics to study. I would suggest overlaying each of the bullet points with your real world experience, and then revisit the Horizon 7 documentation – for example: ‘Troubleshooting agent connectivity issues’ – how do you approach fixing a desktop stuck in ‘Customizing’ state, or ‘Agent unavailable’, or ‘Error’ state – checking the network adapter, horizon agent components, post-sync script, hostname issues etc – this is how I might approach the problem, but if I then revisit the VMware KB’s to look at their best practice steps – there’s additional actions you may not consider e.g. using telnet and nslookup to check DNS resolution to the connection servers – approaching revision in this way will be beneficial as it forces you to consider what you already know and build on it by providing more ideas you can apply in real world situations – which is really what an exam should be about (and it’s refreshing to invest time on a cert that isn’t based on multiple choice…).

The exam problems are formulated around the Horizon 7 documentation as a framework, so refresh yourself on the core features available in horizon and how to configure them – I’m mirroring parts of the blueprint below but this is the backbone of what you should know:

  • Kiosks: preparing the connection servers and creating kiosk clients
  • RDS and Instant Clone Pools/Hosts: setting up application pools, entitlement, instant clone, VM-hosted apps – what settings are available when you setup these features, and how would you test they work?
  • Instant clone pools: pool settings, pool operations, enabling 3D features, HTML access, entitlements, master image creation and preparing an image for deployment including optimizing the hardware and software.
  • Connection Server configuration: backups, storage, authentication options, using vdmadmin, services, troubleshooting replication/ADAM issues.
  • Log files: know how to collect log files from horizon client, agent and appliances (VIDM, UAG, Connection server etc) in the horizon stack.
  • Global entitlements: configuring and exporting.
  • Horizon Administrator: understand the admin console and how you can configure global settings.
  • Horizon Helpdesk: what features are available and how do you use them?
  • Troubleshooting issues with instant clones/agent availability: unable to connect to a VM, installing the horizon agent, dealing with VMware Tools issues.
  • Desktop performance: a bit of a subjective topic – but you should be aware of how to assess desktop performance on a windows machine (what native tool are available to do this…p.s. but you probably never EVER use!)
  • Identity Manager / vIDM: enabling SAML and authentication protocols, adding Horizon resources and syncing objects, entitlement of resources to users and groups.
  • AppVolumes: Appstacks and writeable volumes, managing and using these.
  • Group Policy/AD: A few questions require some AD and group policy administration.
  • ESXi – consider best practices for maintaining uptime for a horizon environment – what features might you configure in vSphere to provide some redundancy?

Second (and third) attempt…

I spent a couple of hours each night for a couple of weeks going over the steps above and at my resit, felt confident in what to expect. On the second attempt I invoked-wisdom and took the below approach. This concludes the post and I hope you get some use from this, I highly recommend studying the VCAP as it’s actually like being at work for a few hours and, because it’s hands-on you’re not wasting time learning acronyms and theory that you’ll never use again.

1/ Immediately fire up Chrome and open tabs for all core appliances, setup RDP sessions to connection servers and open GPMC and AD.

2/ Skip through all the troubleshooting/configuration questions and finish the quick (2 requirements or less) questions.

3/Copy/paste all the vdmadmin -help output into a text file and save it on the desktop of connection server – this prepared me for crafting the answers to several questions and have the UNC path to the vdmadmin dir at hand. The keyboards were crap at the testing centre and you can’t use ctrl+c to copy so get in the habit of right click > copy.

4/Look out for gotcha’s or silly requests in the phrasing of test questions – anticipate ‘typical’ mis-configurations in whatever issue you’re looking at.

5/ I flagged a couple of questions with VMware because I felt the wording was very poor/confusing – obviously there is an expectation of competence with a VCAP, but there are also multiple ways to answer a couple of the questions and I feel I fixed a particular group policy issue with a perfectly acceptable solution that I would implement in the real world, but it was not the answer VMware were expecting. My advice here is to try and consider what is the path of least resistance with a given fix i.e. what can you do to minimize the amount of configuration changes whilst still addressing the problem?


I passed on the third attempt with a score of 300/350 – I had hoped to do better but a pass is a pass..! Onto the Design exam and further posts to follow.

Good luck and thanks for reading.



Configuring Windows Defender AV for VDI

Windows Defender AV for non-persistent instant clone desktops is a lightweight and free AV solution for VDI that is growing in popularity as an alternative to typical third party options as people move to O365 and want to align themselves with Microsoft across their software stack.

Below is a quick guide on how to configure Defender for Endpoint (not ATP) which is a free version of Defender included with E3 O365 licensing using.

A file share is used as the source for definition files. I recently had to setup a proof of concept of this for a client who had been using McAfee ENS and we saw a notable improvement in performance and overall desktop experience.

The guide does not cover how to configure VM’s to use MMPC, WSUS , Cloud based definitons or ATP/MAPS.

Environment: VMWare Instant Clones, Win 10 1909.

What you’ll need

  • 1x SMB file and an endpoint for handling the scheduled tasks needed for Defender definition updates
  • 2x scheduled tasks, one to perform the definition download and unpack, and a second to clean-up old definitions. Both scripts provided.
  • VDI specific Defender settings that are configured on local group policy on the master image, and remaining settings configured on domain group policy.

Before getting started..

  • Check you have the latest ADMX templates for your OS.
  • Use a clean build, ideally with an image that has not had any AV agent previously installed.

Step 1: Setup a share and scheduled tasks to download, unpack and clean-up definitions…

Identify a virtual machine/server/desktop or some endpoint that will be responsible for running the scheduled tasks for fetching definitions and storing them in an SMB file share. The endpoint will require internet access and I refer to this machine as the management VM.

Create an SMB file share to store definitions.

Setup a file share that will store the unpacked definitions. The below example resides in C:\wdav-update on the management VM. I recommend using the same folder names as this will tie together with the download script that will be used later on.

Share permission: Authenticated Users: Read

Folder Permission: Authenticated Users: Read/Execute, SYSTEM: Read/Writed

Get-SMBShareAccess -name wdav-update result should mirror the above

*IMPORTANT* if you provide FULL CONTROL to the folder or share, then you may experience the definitions being automatically purged by the child VM’s after they self-update, making the definitions unavailable at next boot . From my limited testing this behaviour appeared to be by design can’t be controlled by any GPO settings, so avoid this by setting the NTFS permissions correctly.

Create scheduled tasks to download definitions

Microsoft provide the following PS script which handles downloading and unpacking of definitions. There is an alternative script available here but I found the below script does the job and is easier to understand. Adjust the value for $vdmpathbase accordingly, but do not change the [0000…] folder naming convention. This is required otherwise the child VM’s will not be able to parse the folders and will fail to self-update.

$vdmpathbase = "$env:systemdrive\wdav-update\{00000000-0000-0000-0000-"
$vdmpathtime = Get-Date -format "yMMddHHmmss"
$vdmpath = $vdmpathbase + $vdmpathtime + '}'
$vdmpackage = $vdmpath + '\mpam-fe.exe'
New-Item -ItemType Directory -Force -Path $vdmpath | Out-Null
Invoke-WebRequest -Uri '' -OutFile $vdmpackage
cmd /c "cd $vdmpath & c: & mpam-fe.exe /x"

Add a clean-up task…

I configured the below task to clean-up any definition files older than 3 days. Configure this as a scheduled task to run daily.

Get-Childitem "C:\wdav-update" |
 Where {$_.CreationTime -lt (get-date).adddays(-3)} | Remove-Item -recurse -force

Tips for configuring the scheduled tasks:

-Configure definition update to run every 2 or 4 hours , typically MS publish new definitions twice per day, around 8-12 hours between each update.

– If the scheduled tasks are failing, ensure the account used to run the task (local SYSTEM or service account) has internet access – you may need to allow unauthenticated traffic from your management machine if using the SYSTEM account. If you use a zScaler/Proxy device and authenticate clients using a .pac file then you may need to launch IE as the SYSTEM account (on your management VM) and configure the .pac file accordinalty. To do this , download PSExec and run the below command to launch IE in the context of SYSTEM, then configure the .pac file in IE settings.

psexec.exe -i -s "c:\program files\internet explorer\iexplore.exe"

Step 2: Configure Defender local group policy settings on your master image

Defender for non-persistent VDI relies on several local group policy settings being baked into your image to ensure they are available at boot time. Configure the following 5 settings via gpedit.msc on your master image.

Location: Computer Configuration\Administrative Templates\Windows Components\Windows Defender Antivirus\Security Intelligence Updates

IMPORTANT: You must configure Define security intelligence location for VDI clients and Define file shares for downloading security intelligence updates . If you do not configure both, the service will not work.

Values to use:

Define the order of sources for downloading security intelligence: FileShares

Define Security intelligence location for VDI clients: \\yourfileserver\wdav-update

This concludes the minimal settings that are required on the master image.


  • You may want to use LGPO.exe to export a template of the Defender settings for your environment for quick setup in future, or add to an MDT task-sequence for your image builds.
  • If your master image has picked up policies you don’t need or for some reason you’ve had your hand forced to use a crappy image – you can wipe all the local and domain policy by running the below command (elevated). This will wipe all local policy WARNING – do this at your own peril (it will remove OSOT optimizations and all domain+local policy). Remember to re-join to domain and update policy afterwards.
    • RD /S /Q "%WinDir%\System32\GroupPolicyUsers" && RD /S /Q "%WinDir%\System32\GroupPolicy"

Install A BASELINE set of defender av DEFINITIONS

  • If your enterprise has never used Defender before and/or has used a different AV product to date, then it’s highly likely you’ll have domain policy in place to disable Defender and/or your base image will have no pre-existing Defender engine/definitions installed. In this case, you may have to install a baseline definition pack so the Defender engine is activated in the build. This may not apply to all environments but I experienced VM’s failing to update on their first boot because no existing definitions were installed. If this happens, Download the latest definition set from Microsoft and install the mpam-fe.exe file – this will install a definition pack and give you an engine status/last updated point to work from.

Step 3: Configure Defender domain group policy settings…

There’s a plethora of settings for Defender and I won’t cover every setting here. The high level suggestions are covered in the Microsoft blogs – so refer to these, but also be aware that services like MAPS and ATP rely on many of the options available – and we’re not configuring these services in this blog post – only the ‘barebones’ AV product. Some examples of VDI-friendly settings you may want to use are below.

Important: do not configure any of the settings configured in Step 1 on the master using local policy on our domain group policy.

\Windows Defender Antivirus

  • Turn off windows Defender: Disabled
  • Randomize Scheduled tasks times: Enabled


  • Allow users to pause scan: Disabled
  • Check for the latest virus and spyware security intelligence before running a scheduled scan: Enable

\Security Intelligence Updates

  • Specify the interval to check for security intelligence updates: 2 hours

Step 4: Verify that it all works!

So lets recap on what we’ve done;

  • We’ve setup a file share and it’s populating every 2 hours with the latest definition files, unpacked, and ready to be read by our VM’s. We have the necessary NTFS and share permissions in place to make our \wdav-update share accessible from the VM’s and it can be read/written to by the SYSTEM account and/or your service account responsible for running the scheduled tasks.
  • Your master image has the necessary local group policy settings required at boot so the VM’s should be reading from the share and self-updating at every logon, and this should be reflected in the Virus and Threat Protection console in Windows on the VM’s, example below.
  • Your domain group policy settings are configured to manage things like scan times, quarantine behavior, UI and notifications etc and critically you’ve checked the Disable Windows Defender policy is set to disable..!

Spin up your VM’s and check the below log file – search: UpdateEngine – here you can see the subfolders in our definition share being traversed. The log output Skipped verification….Due to PPL is expected and this does not indicate an error. Any errors will be indicated in the entry that begins: UpdateEngine start:


Virus & threat protection settings should show Last Update: today’s date

To Hell and Back with Hybrid AD Join for VDI

*Update 22/01/22 After much effort spent getting this to work at a customer site, it turns out there was never any need to have conditional access enforcing VDI devices to be hybrid-joined. By turning off the conditional access policy that checks the device is Azure-AD joined, there was no longer any issue. Note, if you’re using a zscaler you’ll need to configure source IP anchoring as well.

*Update 31/07/21 After migrating a customer from Appsense to VMware DEM I had to find a new method to perform the hybrid join. The below article now provides two methods for performing the join.

Read this post if you’re having problems performing Hybrid Azure AD join on non-persistent VDI. This post covers the how to configure Hybrid AD join on VDI , how we discovered it was broken and a clean solution to fix it.

The running environment was Windows 10 1909, VMWare Instant Clones on Horizon 7.10, with zScaler proxy (.pac files).

For the solution, click here or scroll to end of article.

How to configure Hybrid AD join and why it might be failing for you…

In our case, hybrid AD join was always broken – we just hadn’t noticed because the device join was successful which is all that is required for O365 services to work (Outlook gets a license – everyone is happy!) but the user PRT token (which I’ll refer to as user-join) was failing – which, if you have InTune in place for MDM policies and all that fancy stuff – you may find these devices are broken when the VDI is in use.

Microsoft offer very little guidance on how to implement Hybrid AD join on VDI but Google yields a lot of negative feedback from folks implementing this for VDI. This VMware thread was helpful in our discovery, and the guidance from Microsoft is helpful, but not as detailed as it should be.

Microsoft’s suggestions are:

Implement dsregcmd /join as part of VM boot sequence.

DO NOT execute dsregcmd /leave as part of VM shutdown/restart process.

  Define and implement process for managing stale devices.

We used a start-up task to perform /join. 

A .bat file or powershell can perform the join as follows, and configure this to run as a start-up task. Note, the task should be ran under the context of the SYSTEM account, and ensure your network is configured to allow this traffic (see zScaler section).

dsregcmd.exe /join

Master Image

You should ensure your master image does not perform an AAD join at all.  You should run the /leave command  as SYSTEM account  prior to sealing your image and taking a snapshot, although we would often forget to do this. Whether this contributed to the issues covered, I’m not sure. Additionally, some threads suggest your master image should not be domain-joined – in our case, the master image IS domain joined, but was NOT AAD joined.

Use PSExec to perform a /Leave command as SYSTEM account:

Psexec -I -s dsregcmd.exe /leave

zScaler .pac on VDI for Hybrid AD Join

If you’re using a zScaler to manage internet traffic you may find that Hybrid AD join fails because the traffic is sent from the VM’s under the context of the SYSTEM account and if no .PAC file is configured against that account, then it will fail (unless you allow unauthenticated traffic on your zscaler devices). If we also throw into the mix that Microsoft recommend you join AAD during device start-up – your user will not have authenticated to zScaler when the /join takes place, so you must configure this.

On your master image, launch Internet Explorer as SYSTEM account, and then manually configure the .PAC file manually. Download PSTools and then run the following command from an elevated cmd prompt:

Psexec -I -s “c:\program files\internet explorer\iexplorer.exe”

The above steps explain how we were configured for Hybrid AD join BEFORE we discovered it was not working. Read on for the discovery, and adjustments we made. Click here for the solution.

How to identify a VM has failed Hybrid AD Join

As a large enterprise with multiple VDI sites managed by different teams, we discovered some sites were performing the /join during the ‘Desktop Created’ stage of the logon process (i.e. once the user is logged In and desktop shell fully loaded) – in these pools we saw the device join was successful,  but user join (PRT token) was unsuccessful – this is because  the user was not logging into an AAD-joined device, so the device was deemed unauthorized to receive a PRT token.

  1. Open cmd prompt and run: dsregcmd /status 
  2. Review the output –note you may also see that the Tenant Name is blank in your output. The device will show as joined, but no PRT/User join had taken place –

Device State shows successful AAD join:

User-join has failed and the AzureADPrt token is not present.

Contrary to MS guidance we experimented with adding a /leave command at logoff – on these pools we saw the object in AAD was updated more accurately in Azure – the ‘Last Activity’ times reflecting the join/leave times of when the desktop sessions were in use.  Howeverthe underlying lesson here is that the device must be joined first then the user is logging into an authorized device and a second /join should take place to fetch the user PRT token.

On the pools configured to use a start-up taskwe found the device join would periodically fail – but this became more frequent as time passed until we had complete failure of all devices in a given pool.

VM template objects flooding Azure AD

We searched AAD to compare on-prem device names to their records in AAD and discovered we had a ton of VM’s joining AAD under the machine name of itXXXX – this is the internal template object which is created by ESXi when a new snapshot is published to a desktop pool. AAD was being flooded with these objects every time we changed the snapshot on a desktop pool.

VM’s were joining AAD successfully (device-join only) but their ID did not match their counter-part object in AAD – instead, it matched the internal VM template.

 At this point we knew that when a new snapshot was published, a new AAD object was being created with the VM’s template account ID. Additionally, it proved the /join was taking place too early in the logon process (at machine start-up) – and instead of joining the hostname of the VM that is provided by QuickPrep (e.g. PROD-VM-1)  the ID of the instant clone template was being used to join the machine to AAD.

To verify this:

  1. Open AAD and search for device name: it

Note, this applies to VMware Instant Clones environments only, Citrix and Hyper-V hypervisors will use a different provisioning process, check your vendor documentation to know what to search for)

Template VM objects in AAD –

Duplicate VM device ID’s

Another symptom of this issue was VM’s would recycle their Device ID – we found the same Device ID (after the device had joined AAD) was in use by other VM’s in the same pool. Presumably this is a hangover from previous symptom.

  1. Take 2 VM’s from the same pool, open CMD prompt and run dsreg
  2. cmd /status, compare the device ID’s on both devices – are they identical?

Verifying AAD Join process

To check if your VM’s are joining AAD with an incorrect computer name:

  1. Check the local VM event log Applications and Services LogMicrosoft/Windows/User Device Registration for event ID 335.
  2. Note, the computer name is itXXXX , user SYSTEM.

Let’s recap what we’ve learned so far:

  • VM’s are joining AAD with the wrong computer name
  • AAD is populated with stale records for our VM’s
  • Our VM’s are recycling device ID’s
  • The User-join (PRT token) is not working

After several hours of toil, testing and swearing, We tried moving the /join to different stages of the logon sequence, but only found Start-up to be ‘successful’ for the device-join. During testing we removed the /join altogether – and low and behold, we discovered the VM’s were still joining AAD – this is because there are 3 scheduled tasks baked into the Windows 10 1909 OS to perform auto-AAD join. 

Microsoft don’t tell you this in their VDI guide because they prefer ‘the Community’ to figure it out…they’re real nice like that.

Configuring Hybrid AD for VDI the right way! #how-to-configure-hybrid-ad-join-for-vdi

Method 1

1/ Perform the /join operation TWICE, once at Start-up, and again before the desktop shell has loaded.This ensures the the Device and the User PRT token are both issued succesfully.

2/ Ensure the dsregcmd.exe /join operation is managed by your profile management tool. Don’t try to mix combinations of scheduled tasks/group policy/profile tool.

3/ Delete the Automatic Device Join scheduled task. This was the root cause of all our pain. The task will perform a join under user context and has 2 triggers – a ‘special event’ and at logon.

4/ Always perform dsregcmd /leave on your master image. Ideally, avoid the master image from joining AAD in the first place.

5/ (Optional) Add a /leave command at logoff of the VM. This is unsupported by Microsoft, the only benefit we found from including this was the ‘Joined’ and ‘Last Activity’ timestamp was kept up to date in Azure AD – but again, not supported.

6/ (Optional) Set the machine GPO ‘Windows Components/Device Registration/Register domain joined computers as devices‘ to disabled. This helps keep things tidy and you can be confident the join is only handled by your profile management tool.

**Alternative Method**

I recently had to decommission Appsense for a customer and move them to VMware DEM. In doing so, the method described above had to be changed. Although DEM can run tasks at Startup of the VM (it hi-jacks the native group policy startup/logoff scripts) which isn’t suitable for performing a /join because the template account for the pool is then joined to Azure AD. Which we don’t want. Thanks to some feedback on the DEM forums, I’ve found the below method works nicely:

1/ Configure a .bat file that has a /leave and /join. You’ll call this as the post-synchronization script when you configure the pool. Example file.

cd c:\windows\system32
dsregcmd.exe /leave
dsregcmd.exe /join

2/ Make the file available on your master image, ideally in the C:\ root somewhere and configure it as the post-synchronization script for the pool.

3/ You should now see the devices populate in AAD when the pool is being composed. When a user logs in , because the VM is now ‘trusted’ the PRT token should be issued. Microsoft does not support the /leave as part of non-persistent devices so I’ve ommitted this. It is possible to add a /leave command (perhaps as a shutdown script), but we’ve discovered no issues with leaving the devices joined in AAD indefinitely.

Master Image configuration

Step 1: Delete the Auto-Join scheduled task in Win 10 1909

  1. On your master image open task scheduler: Microsoft > Windows >Workplace Join
  • Delete the Auto-Join task – this must be deleted and not disabled – because it’s a system task.
  • The remaining 2 tasks should be left in their default state – they should not require any manual intervention. If these tasks are disabled or not present on your image – then check OSOT or group policy if these are being deleted by an upstream policy.

Step 2: Remove your master image from AAD

  1. Launch psexec from an administrative command prompt using: psexec.exe -i -s dsregcmd.exe /leave
  2. You may see the below exit code 0.
  3. Confirm the /leave was successful by checking AAD – you should not see the machine account, and the /status output should be as below.

/status output when device has left

Step 3: Remove existing itXXXX or stale records from Azure AD

  1. Remove any of the stale device records from AAD. This should include the itXXXX devices , and any VM’s in pools your going to test in.

Step 4 (optional): Bake your user profile configuration into the master image

If you’re unlucky enough to use AppSense or a similar tool – you may have to bake your configuration into the master image. Other profile management tools may not require this step.

Profile Management Tool Configuration

Step 4: Configure the dsregcmd /join operations

Start-up task:

  1. Configure the 1st /join operation during Start-up of the machine (or machine boot).

2. Scope this to only apply to machines with your VM naming conventions – this ensure the correct devices join AAD, but also prevent the itXXX devices joining (or your master images).  If you have no profile management tool, then this might work with scheduled tasks or a group policy object, but we did not validate this.

Pre-Desktop task:

  • Perform a 2nd /join operation during the ‘Pre-Desktop’ stage– this is the point at which user authentication has completed, but the desktop is still loading. This should ensure the PRT is issued to the device, and also provides a backup to one of the scheduled tasks (re-sync) which does the same thing.

Has this fixed it for you?

1/ We no longer need to delete ‘stale’ AAD objects – there is only 1 AAD object per VM. Each VM joins to the same AAD object – no duplication, no dodgy device ID.

2/ When a new snapshot is published, we did not see the itXXXX devices appearing in AAD (clean joins!).

2/ User-join was always successful – this is probably because the Auto-Join scheduled task is not interfering with the registration process.

I hope this helps someone, if you find other solutions or suggestions to improve on this find I’d love to know

How to Improve VDI Logon Times

Keep your house tidy!


It only takes a mouse click to break an environment – and recently I found myself trawling through log files to investigate slow logon times with VMWare DEM – the root cause was, as always, frustratingly trivial – a deleted AD group that was still being referenced in the DEM config,  but the steps taken to identify this can help you improve your VDI logon times across your estate (…assuming  your our employer cares about this!). The below principles can be used in any VDI environment with a profile management tool in place.

I’ve split this into 2 sections. The first section How to troubleshoot a logon issue with VMWare DEM includes the actual steps taken to fix aforementioned issue. The second section 5 Tips to Improve VDI Logon Times offers a few ideas to consider in your environment.

How to troubleshoot slow logon with VMWare DEM

  1. First we need to enable granular logging so we can see what is happening during the logon process. For VMWare DEM you can do this by creating a text file named FlexDebug.txt and copy this into the Archive\Logs folder of the affected user.  At logon, FlexEngine service reads the flag text file and logs at a more granular level to the FlexEngine.log file. Deleting the .txt file will revert your logging level back to INFO (or however it is configured in your DEM GPO).

Turn on debug logging in Profile Unity

Turn on debug logging in VMware DEM

2. Log the user out of any open desktop sessions, then delete their FlexEngine.log file so we have a clean log to work with.

3. Log them back on. Once the logon cycle completes, read through the timestamps of logon events and look for gaps of more than 1 or 2s.

Example 1

In total, the below log file shows a gap of 28s where DEM was stuck trying to process erroneous data. The first event is a failed AD group lookup that wasted around 12s over 2 events. The AD group had been deleted from AD, but hasn’t been removed from the UEM config settings.


How to quickly identify a bad settings in your DEM config:

If you’re having trouble locating the offending setting in the GUI of DEM Management Console, then save time by searching the .ini config files directly:

  1. Browse to your UEM Config folder.
  2. Use windows explorer search bar and type content:  to search for whatever text/setting/error/AD group/value is failing to process. This will search the contents of the .INI config files for your DEM installation and quickly identify where your problem lies.


Example 2

Citrix registry value ‘LogOffCheckSysModules’ exists, but does not contain ‘FlexEngine.exe’

This error is caused by an AppVolume package (Adobe Professional) which created the above value in HKLM registry tree. Updating the AppVolume package and deleting the above registry key fixed this.


Issues like these cause overhead on your service desks, remember to keep your house tidy and have regular check-up’s on your logon times. 

Continue reading

Packaging Bloomberg Professional for VDI using AppVolumes or Liquidware FlexApp


The following post runs through how to install and package Bloomberg Professional for a VDI environment. The below example uses Liquidware’s FlexApp to do this, but the ideas below are applicable to AppVolumes with VMware DEM to manage the post-deployment script.

Version: This is intended for users of Bloomberg Anywhere and covers how to package and deploy Bloomberg Professional (Full Terminal).

Bloomberg Professional contains Office Tools (MS Office Add-In) and a full standalone desktop client.

Install on your capture VM

  1. Download the Bloomberg Full Terminal Installation  

2. Run the installer on your provisioning VM selecting Private IP Network as the environment type.

3. Launch the software and click past the connection wizard until you reach the login screen – you don’t want your users to see/do this!

4. Bloomberg has minimum requirements of Read/Write to the following HKLM registry key and subkeys. If you have UAC enabled, you need to set permissions against these keys to allow users R/W access to:


These permissions can’t be captured using AppVolumes or FlexApp because they’re machine-level settings, so we need to use a post-deployment script to add the permissions to the registry after the app has mounted to the desktop at logon time.

There’s a few methods for doing this and at the time we

Configure a post-deployment script using subinacl

The following script should be saved as a .bat file.

1. Download SubinACL

2. Extract the subinacl.exe to a network folder that your users can access.

3. Create the post-deployment script and deploy it, there’s a few ways to do this:

For Liquidware FlexApp – add this script as a post-deployment script – see this guide: ‘App Package Scripts’ section

For AppVolumes –  ideally you should use DEM (formerly UEM) to run the script elevated, at logon or you may need to use Group Policy to run a logon script and scope it against the Bloomberg users.

Another (untested!) option, you could try editing the snapvol.cfg file within AppVolumes – if this works for you, please let me know!

The below can be copied into a .bat file to be executed after the application has been deployed to your VDI desktop(s).

\\\netlogon\AFolderShare\Scripts\subinacl.exe /subkeyreg “HKEY_LOCAL_MACHINE\Software\wow6432node\Bloomberg L.P.” /grant=Everyone=F


1. Ensure subinacl and the .bat script sit in the same folder, ideally your netlogon share. If storing elsewhere, ensure the logged on user has rights to read/execute from that location.

2. Typically Bloomberg allows you to perform an APOD creation – this installs a generic license key which then lets a Bloomberg Anywhere user log in. If you need to configure this follow these steps: once you’ve installed the app on your capture VM, type CONN in the Bloomberg window to see the connection wizard. Under the Connections tab, click Submit. This will create a generic key code and allow the user to login using their Anywhere login creds

Bloomberg Minimum Requirements and File Rights.

3. Your Bloomberg users might not want the Office Add-Ins – to disable these, for ideas on how to disable office add-ins and manage load behavior

3. If your placing a shortcut to Bloomberg on the desktop, create this in: C:\Users\Public\Public Desktop 

4. Bloomberg requires updating every 3 months, add this to your maintenance schedule!