Connection delay until an error is reported when you access a nonexistent NFS share on a Windows Server-based computer

Applies to: Windows Server 2012 R2 DatacenterWindows Server 2012 R2 StandardWindows Server 2012 Datacenter

Symptoms


Consider the following scenario:
  • You have a server that is running in Windows Server 2012 R2 or Windows Server 2012.
  • You start the Client for NFS service on a client computer.
  • You try to access the server by using a Universal Naming Convention (UNC) path, such as the "\\Servername\sharename" path.
  • The "sharename" shared folder does not exist on the server.
  • The server runs only the Server Message Block (SMB) file service and not the NFS file service.
In this scenario, a connection delay that is longer than 40 seconds occurs, and then you receive an error message that states the path is not found.

Cause


This issue occurs because the client uses the TCP connection two times to connect to the NSF server, and both fail.

When a Windows client accesses a UNC path, it tries to contact the server over all installed network providers. During this period, the client first tries to contact the NFS server over the SMB protocol, and then the server responds quickly alongside an error as the shared folder does not exist. 

Then, the client tries to contact the server over NFS protocol. The client opens a TCP connection to the server. As the NFS service does not exist on the target server, the TCP connection times out, and it takes about 20 seconds. Because of the architectural design, the TCP connection tries again. Therefore, it takes more than 40 seconds to present an error message to the client.

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