Once again, Unchecking IPv6 on a NIC Breaks Exchange 2013


It seems like this sentiment has been preached widely but yet I still see customers do this. In fact I’m writing this today because earlier this week I had a customer who’s Information Store Service, as well as the Exchange Transport Services, on Exchange 2013 would not start. Then earlier today a coworker actually did this in a lab which caused the same issue.


Let’s start off with this, The Exchange Server Product Team performs Zero testing or validation on systems with IPv6 Disabled. So that right there should be a good indicator that you’re trailblazing on your own in the land of Exchange (bring a flashlight, it’s dark & scary).

So I’m going to cover two very different things here:

  • Unchecking IPv6 on the NIC adapter (BAD)
  • Properly Disabling IPv6 in the registry (Ok but not recommended by MS)

Unchecking Method (BAD):

Let’s first talk about un-checking IPv6 on your NIC adapters. The problem with this is while the OS still thinks it can & should be using IPv6, the NIC is unable to do so which leads to communications issues. An easy way to test that your OS is still trying to use IPv6 is to ping localhost after you have unchecked IPv6 on your NIC & rebooted. You’re see that you still get an IPv6 response. I actually did a write-up about this topic on the Sysadmin community on Reddit awhile back which you can find here. As a side note, check out the Exchange community a colleague & I moderate on reddit here.

While doing this has always caused sporadic issues with Exchange, Exchange 2013 seems to be even more sensitive in this regard. Since RTM, I’ve seen half a dozen Exchange 2013 issues that were resolved by re-checking IPv6 on the NIC adapter & rebooting. Here’s what I’ve seen so far:

  • Having Ipv6 unchecked when performing an Exchange 2013 install will result in a failed/incomplete installation which will result in having to perform a messy cleanup operation before you can continue.
  • Microsoft Exchange Active Directory Topology Service may not start if the Exchange 2013 server is also a Domain Controller and IPv6 has been unchecked. The solution is to re-check it & reboot the server.
  • Microsoft Exchange Transport Service as well as the Microsoft Exchange Frontend Transport, Microsoft Exchange Transport Submission, & Microsoft Exchange Transport Delivery services may not start if IPv6 has been unchecked on the NIC adapter of an Exchange 2013 Server.
  • Microsoft Exchange Information Store Service may not start if IPv6 has been unchecked on an Exchange 2013 Server.
  • NEW – See MVP Michael Van Horenbeeck’s post on how this can break the Hybrid Configuration Wizard

Disabling IPv6 in the Registry:

I started this post saying that MS does no testing or validation for systems with IPv6 disabled in ANY WAY. However, some customers may actually have reasons for disabling Ipv6. I’m actually interested in hearing them but I also know some customers are very adamant about it. There actually was an issue in the past where Outlook Anywhere wouldn’t work in certain scenarios with IPv6 enabled but this should not be a problem with a fully updated Exchange Server (reference).

I’ll also say that I personally have never had any issues with properly disabling IPv6 in the registry using this method. You basically add a DisabledComponents key to the registry with a value of 8 F’s (ffffffff) & then reboot the server. After this point IPv6 should be fully disabled. I’ve also spoken with a couple Microsoft Support Engineers who have also said that they have personally never seen any issues with disabling it this way; with Windows or Exchange. However, in my opinion you should have a good reason for doing so (and saying you don’t like IPv6 is NOT a good reason).

Lastly, I’d like to add that if you’re utilizing iSCSI on your Exchange server, there should be no issues with unchecking IPv6 on your iSCSI NICs if you choose to do so. The article was specifically in relation to NICs connected to your production/public/MAPI networks. As usual, follow your SAN vendor’s best practices when configuring iSCSI NICs.

Also, here’s a shameless plug for the ExchangeServer subreddit (http://www.reddit.com/r/exchangeserver) which I help moderate (username=ashdrewness). There’s always people such as myself answering questions on there.

15 thoughts on “Once again, Unchecking IPv6 on a NIC Breaks Exchange 2013

  1. Pingback: The UC Architects » Episode 25:

  2. Pingback: IPv6 transition – just get on with it! | Thuktun (Message)

  3. There’s a situation with Gmail and IPv6 it seems. Google will attempt to look up the PTR records for any IPv6 address it sees in the headers of an inbound email and reject any email from such a server if there’s no successful resolution, very likely. Some have decided then to disable IPv6 because of that.

    • I’ve actually heard that as well from someone second hand. In that case disabling it is fine if it’s done the proper way.

  4. Hi Andrew, I´ve a problema with google when i send a gmail domains sometimes i recived this guidelines [2002:b8ad:e112::b8ad:e112 16] Our system has detected that this message does not meet IPv6 sending guidelines regarding PTR records and authentication. Please review https://support.google.com/mail/?p=ipv6_authentication_error for more information. oy3si856858obb.85 – gsmtp
    I try with mi ISP register PTR but it doesn´t work .. Any idea ? ….

  5. Pingback: » Exchange – IPv6, você desmarca?!

  6. Pingback: » Exchange 2013 – Requisitos de rede para o DAG

  7. Still during co-existence Migration of Exchange 2007 / 2013 the customers needs to DISABLE IPV6 on the 2007 to get certain things working. The information is sporadic seen in Chanell 9 Powerpoints from Technet days. So when people disable it (Via Keys) you may have to understand why. We woul dlike to know from Microsoft in Regards to their well pushed technology Direct Access which is based on IPV6 this comes together once 😉

  8. Pingback: My most commonly used blog posts for troubleshooting Exchange | A bit of Exchange & Office 365

  9. Andrew
    I have a subscription to Exchange Online for home use. This is an outstanding set up but something happened either in late october or early November of 2016. Prior to then, everything worked fine. I was out of the country but somewhere in that time-frame connecting to the Exchange online failed (using Office 365 (Outlook)). Using some diagnostics I was able to narrow it down to IPv6. If I turn off IPv6 (Windows 10 pro) everything works fine but the same exact problem exists with the Android app, Touchdown (Android version 6 on a Samsung S7). If I am in my home environment with IPv6 coming through, touchdown will not connect to the online exchange server. I can use wireless through Verizon and Touchdown works fine. It is only through my home environment (Time Warner @ 300 megabytes on a Technicolor cable modem) that the problem exists.Turning off IPv6 works for the PC but since the wifi connection to the phone continues with IPv6 Touchdown fails. At first I thought it was TWC problem; their solution(s) and level three helpdesk were basically useless. Tried level 3 help at microsoft. STill no help. I really must get this fixed as it impacts three separate pieces of software, all trying to get to the exchange account. Additional details. Android Outlook Web App(OWA) works fine in this environment. Again it is ONLY with IPv6 turned on that failure for Office 365 to connect to exchange online fails. The other two pieces of software are via a wireless network with IPv6 on. I have tried getting inside the router but no options for turning off IPv6 can be found plus I would rather fix the problem than to turn IPv6 off. I desperately need help

    Anyone anywhere know how to solve this dilemma or how to direct me to the right person?

    Paul Covington

    • I know some external services don’t function if there’s not external IPv6 DNS records (AAAA); things like Gmail.com blocking your emails and such. You could certainly test disabling IPv6 the proper way (via registry) and see if that’s the easier/more managable solution.

      • Andrew, thanks ever so much for the response but disabling IPv6 through Windows DOES work just fine FOR THE PC ONLY without changing the registry. In other words, disabling IPv6 in Windows 10 allows Outlook to connect to Exchange Online without difficulty. However, this has NO EFFECT on the ANDROID APPLICATION called Touchdown, which does not use Windows. Touchdown, which also connects to Exchange Online via wireless connection completely bypassing Windows, fails to connect in an IPv6 environment. And to make matters worse, there is yet another piece of software in my home environment that fails to connect as well (I am assuming this is IPv6 as well since it was working fine until something changed in later October/early November 2016 and this software stopped connecting to an “email server” (unable to tell what it is referencing) at the same time Outlook started to fail and Touchdown failed. But I have no way of checking this proprietary software to verify the problem).

        I know for a fact that the Android problem is IPv6 as well as I can reproduce the problem in other wireless networks that have IPv6 on and those that don’t have IPv6 it connects to Exchange Online just fine.

        I am convinced this is isolated to a Microsoft Exchange Online issue as all other software works. And to reiterate in Windows 10, disabling IPv6 fixes the inability for Outlook to connect to Exchange but does nothing to the Android situation nor the other piece of software, both of which are independent of Windows. Again, is there ANYTHING you can suggest that can help here? Is there ANYTHING that MS did during that timeframe (late Oct/Early November) that might have precipitated this problem

        Again any help from anyone with respect to this problem would be much appreciated.


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