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

8 Comments

  1. 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 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.

  3. 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…

  4. +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.

  5. 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.

  6. 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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