Confusing behavior in Exchange 2007/2010 when changing Hub Transport DNS configuration

I recently ran into a configuration issue in Exchange 2007/2010 that left me scratching my head in bewilderment.  After noticing some DNS resolution issues between several hub transport servers I began looking at individually and manually configuring DNS resolution settings on specific Exchange servers.  In ESM I went to “Server Configuration > Hub Transport” and viewed the properties of each server.  On the “Internal DNS lookups” and “External DNS lookups” tabs you get the option to choose either the DNS configuration from a specific network adapter or manually enter the DNS servers to use.

To save time, I began using the drop down selection of specific network adapters to grab the DNS servers I wanted.  However, there is an important “gotcha” here that is not indicated in the GUI or anywhere else that I’ve seen.  Basically what is happening is that when you use the drop down NIC selections to grab DNS, what you are doing is querying the NICs of the server on which you are running ESM.  So what happened in my case is that incorrect DNS servers were being assigned to remote Exchange servers because I assumed that the NICs being listed in the drop down were the NICs physically installed on the remote server for which I was viewing the properties.  Big mistake!

I started noticing events in the logs complaining about inability to resolve DNS hosts.  Once I started investigating this it dawned on me that the names of the NICs in the drop down listing never changed as I viewed the properties of different servers.  It just happened that the NIC I chose did not have any DNS servers configured, so I was basically configuring those specific Exchange servers with no DNS at all on the hub transport DNS resolution configuration.

To resolve the issue, I manually specified the DNS servers to use for each specific Exchange server.  That completely resolved the problem and got mail flowing again.

Just kind of curious why Microsoft would allow you to manage remote servers from one location/instance of ESM but only show you the NICs on the local server when configuring remote server hub transport properties.

De-evolving technologically

A lot has happened since I last posted, but I thought it would be good to post a quick update on the changes I’ve made technologically over the last few months.

The first major change is the decommissioning of my personal Exchange mail system.  My home server setup was getting far too complex and expensive to maintain so it was decided to do some downsizing and basically get rid of a bunch of servers.  At the time I began to remove servers, there was 6 being used full time.  It got to a point where I had built a powerful white-box server on which to run VMWare ESXi 5 which allowed me to virtualize all of my servers.  There were 2 for AD/DNS/DHCP and 2 for Exchange 2010 in a DAG and 1 for simple/general tasks like backups and game servers.

To be honest, my wife and I got quite accustomed to having enterprise level features in our home e-mail solution.  As someone with about 12 years of Exchange experience I had it setup right which included custom domain names, SSL certificate, networking to support ActiveSync for our iPhones, etc.  I had wanted to simplify things for quite a while, but never could find just the right solution to handle our e-mail and calendaring in a way that would remain highly functional and not be difficult to migrate to.  Then along came a new service by Microsoft called Outlook.com.  Long story short, outlook.com is everything we needed to get rid of Exchange and simplify the home setup.

Our email, calendars, contacts, etc – were all easily migrated to Outlook.com.  Of course I had to dump about 8GB of archived messages to PST files out of Exchange, but thats a normal part of the process.  For the time being, we’re still using Microsoft Outlook to grab old messages, but for all new messaging features we’re going with Windows Live Mail.  It integrates nicely with Outlook.com and gives us a very nice user experience with pretty much all of the features that we were accustomed to while using Exchange.

Unfortunately, the networking side of things hasn’t transitioned quite so easily.  When we had all of these servers running they were responsible for most of our networking services, like DNS/DHCP.  Transitioning to router based network services was a bit of a challenge.  I ended up buying an Asus RT-N66U dual band 802.11N Wi-Fi router.  The Verizon FIOS router is forwarding all traffic to the Asus router (DMZ).  In the Asus router I’m doing all my port forwarding rather than having the Verizon router handle of that.  Mainly because the ASUS router won’t allow many of its advanced features if its configured as a mere AP, it must be in router mode for the bells and whistles.

An unfortunate side-effect of this transition is that all of our Apple Devices appear to be rather slow on Wi-Fi using the new home network setup.  I’ve run lots of diagnostics and tried many tweaks but nothing I’ve done so far has restored pre-transition device speed for the iDevices.  Strangely enough my laptop works fairly well on both the 2.4GHz and 5GHz Wi-Fi Networks.  I suspect there is some advanced tweaking that could be done to improve the iDevice performance over Wi-Fi, but so far I haven’t figured it out.

At this point, my office has one nice PC in it, a PC that is quiet and easy to maintain. The big server is now going to go up for sale, hopefully on Craigslist.  After adding everything up, it seems I have approximately $1,200 worth of server/parts available for sale.  This was a great machine, dual quad core Opteron 2.2GHz CPUs, 32GB DDR2 memory, 6 SATA HDD for over 5 TB of disk space, etc.  This machine was perfect for virtualizing servers, the only downside is the noise and heat.

To sum up, I’m no longer running a bunch of servers at home.  No more Exchange for home messaging, no more noise, no more extra heat in the office, its all gone.  And its interesting how quickly we grew accustomed to the noise in the office and how much we enjoy the quiet now that its gone.

In addition to the servers being removed, I also finally got us off the Ooma VOIP service.  Someone purchased the Ooma box from me via craigslist and took it off my hands.  Since we’ve bundled phone services with Verizon FIOS there was simply no further need for an additional home phone service.

Outlook.com is handling our messaging needs very nicely.  The web interface is easy to use and very clean.  It supports Active Sync via the Hotmail connector in the Apple Mail client, which is very nice.  The only things we really miss are server based Distribution lists and shared calendars.  However, none of that was a deal-breaker for us.

As a result of the downsizing, it looks like we will be saving approximately $600 a year in services and fees from all of the various resources I needed in order to run such a system at home.  That includes Microsoft licensing and domain names, SSL, etc.  Needless to say this transition is going to be a cost saver with only a few minor networking kinks to work out.