Crossed OWA Sessions

OWA has become one of the most coveted features in any Exchange installation. The ability to safely and securely access email from any web browser is hugely convenient and loved by all. However, the backend behind OWA, while normally straightforward, can present some configuration challenges for large organizations. Seemingly innocuous settings on load balancers, can have a huge impact on the operation of OWA, which as a web service is performing a bit of magic in delivering mail from multiple mailbox servers to users.

One particularly problematic issue is when using a load balancing infrastructure in front of OWA to balance users across multiple CAS servers. Under certain circumstances, load balancers can actually cause OWA sessions to be crossed so that users log in and briefly see another user’s mailbox contents for a finite but definitely tangible amount of time. While the breach may not be long, it is real and in some cases the errant user will even bee able to navigate the mailbox of the other user.

The issue arises in the way many load balancers cache content to improve performance in website loads and will be more prominent with large deployments with thousands of users rather than small deployments where caching of content will be at a lower volume. The load balancer in these cases actually caches chunks and sections of users mailboxes and the links etc, contained therein are logged in on the CAS server itself, so the load balancer, in an attempt to speed up the load time, will deliver another users content to a session without regard to the fact that the content in question needed to be authenticated to be accessed.  Users will often not realize until it is too late, that they are in another users mailbox thanks to the malfunctioning load balancing infrastructure.  Its easy to see how this scenario is problematic.

I haven’t seen this specific scenario addressed clearly and in plain language with most load balancers, and is for that reason that this post exists. Many load balancers will have a list of optimal settings, but its easy to see how these can be overlooked by administrators, who are used to deploying load balancing infrastructure for other static content and don’t realize the potential for these crossed sessions in OWA.

The solution, and this applies to nearly any load balancer out there, is simple. Any settings related to caching content of sessions or optimization needs to be disabled unless the load balancer you are working on has specifically stated that it has integrated settings for OWA.  Ensure that no part of the OWA sessions are being cached on the device, and if you had it enabled and now need to disable, run whatever command is necessary to flush the cache after you are done.

Hope this post can help save someone hours of troubleshooting this issue as it is obscure.


70-410 Installing and Configuring Windows Practice Questions

So I have recently undertaken the endeavour to upgrade my Microsoft cert and attain the full MCSE Server 2012 Server Infrastructure designation. As part of this, I thought it would be helpful to our loyal readers if I included some tips tricks and practice questions that I find useful along the way. With that, please find the first set of 5 unveiled here.  What better project to take for a rainy Vancouver winter that to brush up on all of my IT skills.

Hope you find them useful!

Lets get started:

1.  Of the following, which of these methods is the primary method for transmitting IPv6 traffic across an IPv4 network.

a. Subnetting

b. Extraction

c. Supernetting

d. Tunneling

2.  Which of the following tools would you use to bulk add and later modify active directory objects

a. LDAP Data Interchange Format Directory Exchange (LDIFDE.exe)

b. Comma-Separated Value Directory Exchange (CSVDE.exe)

c. netdom.exe

d. djoin.exe

3.  Which powershell command is correct in syntax and function for adding computer objects in active directory.

a. new-ADComputer –Name <computer name> –path <distinguished name>

b. new activedirectoryobject –computer <name> –distinguishedpath <path>

c. add-ADComputer –Name <computer name> –path <distinguished name>

d.  netadd computer –ADForest –name

4. Which tool is best suited for deploying settings in a security template to all computers in an AD DS domain.

a. Security Templates snap-in

b. Group Policy Object Editor

c. Group Policy Management Console

d. Active Directory Users and Computers

5. To create a passthrough disk in Hyper-V, the disk must be taken _____________.



1. d 2. a 3. a 4. c 5. offline

Hyper-V on Windows Server 2012

Enterprise IT managers and techs all over have become increasingly familiar with names such as Xen, Open Xen, KVM, Virtual Box, VMWare and Hyper-V as the virtualization revolution swings in. With buzz words floating around like Public Cloud, Private Cloud, Hybrid Cloud, IaaS and PaaS, it is no wonder that many professionals don’t know which way to turn for their virtualization needs. In the past, VMWare was definitely the dominant player in the data center whereas the market share for SMB’s has been fragmented with those very same names above. While Hyper-V has always had a good reputation, their has been a fierce battle for supremacy in the virtualization market and the stakes are high. Not unlike a Bill O’Reilly vs. Jon Stewart debate, advocates of both platforms come out swinging when the virtues of either is questioned.  I have never hidden my preference for Hyper-V and with Server 2012 the *LOVE* only grows stronger.  Read on for all of the goodness.

So what is it exactly that now puts Hyper-V at the front of the pack? Quite simply the most convincing of all arguments is the economics one. Hyper-V now offers a built-in feature set that is robust enough for the data center and flexible enough for even a small business at a cost that is significantly less than VMWare. The bang-for-the-buck factor is undeniable and frankly has brought a new level of fervor and excitement to the virtualization realm. Going with Hyper-V means you might have an extra 20K in your pocket for that IT department barbecue, camp out and paintball weekend you always wanted, or if you are in one of those countries where extra money in the budget means a real party – knock yourself out!

While I don’t want to sound like I am the script writer for the latest ShamWow commercial, I can say honestly that there is likely not a business in existence that couldn’t benefit from some of the new features that have been bought to the table with Hyper-V’s latest iteration.

At a glance, we have:
-multiple and simultaneous VM migration and failover
-live migration of storage
-Hyper-V Replica for entire site replication and failover
-Hyper-V extensible switch
-Support for high availability using non-shared storage and notably SMB
-Improved NUMA memory management

...and many many more under-the-hood improvements to make Hyper-V more performant, robust, and reliable. All of this is essentially included with your Windows server licence and with the Windows Server 2012 Datacenter edition you get unlimited virtualization rights. No longer is Hyper-V just cheaper, it is often a cut above VMWare. It is also something that is designed according to Windows style guidelines and is intuitive and easy to manage for IT support staff already familiar with Windows server. (If they turn this into a Metro App, I will pull the article immediately. Please tell me why we need the ability to play Angry Birds on a server designed to be managed remotely from Powershell?) Anyway, the switch to server 2012, even in a data center environment, is compelling for sure.

Anyway, as I play with more of these features in the lab, you can look forward to more insight on each. I look forward to sharing this all with you in the form of writeups and training videos.



Windows 8–A Catastrophe or Sheer Genius?

Well, here we are back again and just in time as we are on the cusp of the next Windows revolution? Or are we? Others are voicing some concerns and seem to feel that we may instead be on the cusp of the next Windows revolt?  So, where do we really stand with all of this? Let’s take an objective look…..

But first, a small digression. As of late, I find myself apologizing  more that writing on the blog as updates became more and more scarce.  I hoping to improve that a bit, so hopefully more content will be appearing on here on a regular basis.  Now, on to the good stuff.

Windows 8 is surely going to be the most controversial Windows release of all time. That is clear. While many will point to major changes in  Windows 95, Windows XP, and Vista, never before has the UI been revamped in such a radical and unfamiliar way. Undoubtedly, many consumers will be left somewhat bewildered when they try and perform routine tasks like “opening My Computer” or “launching the Control Panel” The fact is, the operating system now relies on some fairly subtle gestures to perform some of these routine actions. Admittedly, when I installed the Developer Preview, I actually called up Paul and we both had simultaneous and mutually identical reactions and with a gasp we exclaimed “What have they done?” The truth is, I hated it when I first started using it and quickly uninstalled and replaced it with Ubuntu – which at the time was looking like it might be my next new OS.  At this point I let my interest in Windows 8 sit, digest, regurgitate and I thought evaporate. Whew….glad it went away.

News of the consumer preview was to follow. I had to check it out. I installed it on a Dell Latitude D620 (read – old hardware). The computer booted and it was sluggish and performing poorly. The screen resolution was terrible.  I knew that the video driver was obviously and issue, but this particular model of Dell only has Windows XP drivers available from Dell. My attempts to force those drivers onto the system resulted in all sorts of system errata. Windows update did not return any results for a good driver either. I then went to Windows catalog and began the hunt for a driver with a similar PCI dev/hardware Id. After some hunting, I found a Windows 7 driver. To my delight, this installed. Alright, reboot time….

As the machine spun down, I was expecting the old laptop to groan under the weight of the new and beta quality OS. Much to my surprise, the OS booted in a fashion that was shocking to say the least. It was as if the laptop now had an SSD drive installed it booted so fast. Was this for real?

The speed of Windows 8, truthfully, is nothing less than phenomenal. Despite fumbling my way around the new desktop, it was shocking to see the speed at which applications were launching. Anecdotally, this laptop, despite its age, was orders of magnitude faster than Windows 7, Windows XP, and the Ubuntu install running on it previously. Magnificent.  But speed alone wasn’t going to win me over. Lucky for me a true test for the OS was about to present itself  and even better yet, the test subject was a non-geek, common salary man.

To be continued…….

Hot New iPhone Game – Gem Shock



For those of you that come to our blog regularly, you would know that we have never done a game review before. This isn’t because we don’t game or because we have anything against game reviews themselves, but it is more because games are usually so well covered by other sites that anything we would say would be totally redundant.

It is with pleasure, however, that I bring our readerships attention to a great new game that I have heard about and been playing.

Gem Shock is one of those extremely simple but yet extremely addictive games. It really reminds me of Tetris in its sheer simplicity and potential for addiction. It is great.  Manoeuvring your Gem through the electrified walls while pushing yourself to race against the clock and fighting to get that steady hand you need to win  really is stupefyingly fun!

The game is only $0.99 and is a hoot. Check it out on the itunes app store today and have a go at it…I sure haven’t regretted my purchase!

Here’s a link for the so inclined – Gem Shock:

Copyright © 2010 Paul Guenette and Matthew Sleno.