Copper Contributor

Had 2 offices which had some computers update with Security Update KB5001330.


After reboot they could no longer Map Drives to the server.  (Server 2012)


Can ping Server Local IP Address but the \\"ServerName" Comes back as not found.


When I Remove Update.... Things work like they did before and I can Map Drives and see \\Servername.


Anyone else experiencing this Problem?



2 Replies


After working with Microsoft, we believe that we have found a solution that allows you to keep the critical Microsoft Security Update installed. It appears that this issue can be resolved by enabling "Link Layer Multi-cast Name Resolution" (LLMNR). This is a Windows Group Policy that many users have disabled over the years. Re-enabling it seems to restore proper IP Address resolution which in turn restores connectivity to the Dentrix Database. To enable LLMNR, follow these steps (please note, these steps need to be completed separately on each impacted workstation):

  1. Go to Start>Run and type GPEdit.msc     <press enter>
    • This should open the Local Group Policy Editor 
  2. Use the Group Policy Editor to navigate to Local Computer Policy>Computer Configuration>Administrative Template>Network>DNS Client (see screenshot 1 below)
  3. Double-Click "Turn Off Multicast Name Resolution" 
  4. Mark the radio button labeled "Not Configured"  (see screenshot 2 below)
  5. Click Apply and OK 
  6. Open a Windows Command Prompt Window (Start>Cmd.exe) and enter the command ipconfig /flushdns <press enter>


Thanks for posting the solution as well for others :)