Correct way to disable IPv6, and avoid 5 second Boot delay

Many Windows users ans IT administrators have opted to disable IPv6 to solve Internet connectivity issues, or on the assumption that they are not running any applications or services that use it. Yet others have disabled it because they feel that having both IPv4 and IPv6 enabled, effectively doubled their DNS and Web traffic.

Microsoft explains that this is far from truth. It goes on to explain what are the company’s recommendations about disabling IPv6. But first, let us divert our attention to these standards.

IPv4 is the fourth version in the development of Internet Protocol Internet that routes most traffic on the Internet. The version provides us with 32 bit address. The newer version of IP, that is the IPv6 on the other hand offers us 128 bit addressing capability which means that there would be more number of addresses available for use and making the internet more secure. Check this post to learn more about the difference between IPv4 and IPv6.

IPv6 is a mandatory part of the Windows operating system and it is enabled. Microsoft says its Windows OS was designed specifically with IPv6 present. If IPv6 is disabled on Windows 7 or upper versions, some components such as Remote Assistance, HomeGroup, DirectAccess, and Windows Mail may actually fail to function. The problem gets compounded with a delay in startup time of 5 seconds or more, if IPv6 is disabled.

Disabling IPv6 delayed boot times by 5 seconds

For years, the method practiced regularly to disable IPv6 was setting the DisabledComponents value at 0xFFFFFFFF under the following registry key:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\TCPIP6\Parameters\

However, disabling IPv6 with the above registry value caused a 5 second boot delay in the Pre-Session Init Phase of OS startup.

The reason for the delay is that underlying code requires the upper 24-bits to be zero. Since the upper 24-bits have no meaning, setting a value of 0xFF is functionally identical to the 0xFFFFFFFF setting. Unfortunately, the DisabledComponents setting got documented with an all “F” bitmask. If you used this documented setting this unnecessarily results in a 5 second boot delay, says Microsoft.

Correct way to disable IPv6, and avoid 5 second Boot delay

The Windows versions impacted by the 5 second boot delay include Windows Vista, Windows 7, Windows 8, Windows 8.1, Windows Server 2008, Server Windows Server 2008 R2, Windows Server 2012 and Windows Server 2012 R2.

Correct way to disable IPv6

Now a 5 second boot delay may not matter on servers that rarely reboot, but on client operating systems, especially those that are configured with SSD disk drives where full OS boot times are approaching 30 seconds – it does matter!

Leaving IPv6 enabled on current Windows client and server operating systems remains the best practice configuration.

But if you do wish to disable IPv6, the correct setting to use in environments that legitimately need to disable IPv6 and IPv6 transition technologies is to configure the DisabledComponents registry key with a value of 0xFF, says Microsoft now.

If you have disabled IPv6 by setting DisabledComponents at 0xFFFFFFFF, it might be a good idea to make the change based on these new findings.

Both the Fix IT and the manual steps mentioned in KB929852 have been updated to reflect this change.

Posted by on , in Category Windows with Tags
Anand Khanse is the Admin of TheWindowsClub.com, a 10-year Microsoft MVP Awardee in Windows (2006-16) & a Windows Insider MVP. Please read the entire post & the comments first, create a System Restore Point before making any changes to your system & be careful about any 3rd-party offers while installing freeware.

8 Comments

  1. Lojix Net

    Good article. I have previously found there is still a great deal of debate on whether to disable IPv6 or not. I am wondering if you could shed some light and clear the confusion on the matter…
    What problems are caused by disabling IPv6?
    What are the considerations or potential undesirable effects?
    Some people report random LAN and application side effects and others argue the inherit security flaws don’t currently justify it’s use.
    What do you advise in regards to this?

  2. I have mentioned the problems which may be caused by disabling it. The TechNet article I have mentioned may throw more light on this.

  3. Lojix Net

    I guess they are the authority on this matter. The IPv6 first-request, then IPv4 fall-back process on each communication may be one of the annoying inefficiencies at the moment, but my thoughts on it are unless experiencing any problems which can be isolated to the IP stack, it’s probably best off left.
    Good information Anand, thanks.

  4. XiONKALE

    umm.. . . so how to solve this problem ??? :/ newbie here plz need a step-by-step routine

  5. Zack A

    I am responsible for maintaining over 100 Microsoft servers consisting of domain controllers, SQL servers, IIS Servers, Exchange Servers, SharePoint Servers, File Servers, Print Servers, our PBX server…. you get the idea.
    I have IPv6 disabled on each and every one of them throughout the organization and have not had a single issue – ever. That’s in years of operating this way. We run every server OS variation from 2008 to 2012 R2.

    In fact I have found where having IPv6 enabled CAUSES issues. Take into consideration a domain controller. If you;re running an IPv4 network and do not assign the DC a static IP address, when it reboots it will grab an APIPA IPv6 address that was different than what it had prior to the reboot… You see the problem with that I’m sure – especially since Windows is configured to prefer IPv6 by default… Yea – it can blow up your entire AD infrastructure…. Ask me how I know…

  6. Lojix Net

    +1 …In short, I have no doubt you are correct. I don’t see any reason as to why IPv6 is the preferred protocol. I realize there is finite number of public IPv4 addresses which are fast approaching exhaustion, but around a decade since Windows adoption of IPv6 and about all it does for the vast majority of users is slow down every DNS request their PC makes… When it becomes necessary for me to use, that’s when I will enable it.

  7. Zack A

    In short – if you plan to use it – then it should be properly deployed. But if you’re an IPv4 network and don’t plan and manage it’s use then leaving it on as it is by default will cause you problems like I outlined in my example.
    Either use it and manage it properly – or shut it off. But the out of the box config of having it enabled and preferred by default WILL cause you headaches in an IPv4 network. You don’t want your servers picking their own random IPv6 addresses after every reboot.
    Also I understand the world is out of IPv4 addresses. But those are PUBLIC addresses. My LAN is no where near exhausting the private IPv4 addresses in our subnets. So why do I need to change on the LAN side? Answer is – I don’t.
    The one advantage I see to IPv6 is that it includes space in the IP header for IPSec information. Whereas IPv4 usually resulted in datagram fragmentation if IPSec is employed. Outside of that – I see no advantage at all on the LAN side.

  8. Shashindra Bahadur Singh

    Do you believe since IPv6 makes the internet more secure, this may create a lag or packet loss, if the IPV6 were to be enabled within the router?

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