DirectAccess server cannot ping a DNS server or a domain controller in Windows Server 2012

Applies to: Windows Server 2012 DatacenterWindows Server 2012 DatacenterWindows Server 2012 Essentials More


Consider the following scenario:
  • You configure a Windows Server 2012 server as a DirectAccess server. 
  • The DNS server and the domain controllers in the intranet are IP version 4 (IPv4)-only resources.
  • You configure a DirectAccess client to ping the DNS server or a domain controller for the Network Connectivity Assistant probe.
In this scenario, the DirectAccess server cannot ping the same DNS server or the domain controller at the same time that the DirectAccess client pings the DNS server or the domain controller. Therefore, the DirectAccess server raises a false alarm that either the DNS server or the domain controller is not available. 


This issue occurs because the ID that NAT64 uses for an ICMP packet and the ICMP ID that is generated from the local stack both start from 1. Therefore, NAT64 incorrectly forwards the ICMPv4 Echo Reply message back to the DirectAccess client, even if the message is for the DirectAccess server.

Because the DNS server and the domain controllers are IPv4-only resources, the DirectAccess server uses NAT64 and DNS64 for translation during the communication. When an ICMPv6 packet that must be converted to ICMPv4 arrives at NAT64, NAT64 allocates an ICMP ID to the packet. Because of a conflict ID range, when the DirectAccess server also pings the same DNS server or domain controller, the response is sent back to the DirectAccess client.

  • NAT64 is a mechanism that allows for the IPv6-based communications from the DirectAccess client to the DirectAccess server to be converted from an IPv6 address to an IPv4 address.
  • DNS64 is a mechanism that synthesizes the AAAA records (IPv6 address records) from the A records (address records).


This hotfix is also available at Microsoft Update Catalog

Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem.

If the hotfix is available for download, there is a "Hotfix Download Available" section at the top of this Knowledge Base article. If this section does not appear, submit a request to Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft website: Note The "Hotfix Download Available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.


To apply this hotfix, you must be running Windows Server 2012.

Registry information

To apply the hotfix in this package, you do not have to make any changes to the registry.

Restart requirement

You must restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace a previously released hotfix.


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

More Information

For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base:
824684 Description of the standard terminology that is used to describe Microsoft software updates