Microsoft KB Archive/175372

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MS Loopback Adapter Installed During SBS Setup If No NIC Is Detected

Article ID: 175372

Article Last Modified on 10/30/2006


  • Microsoft BackOffice Small Business Server 4.0
  • Microsoft BackOffice Small Business Server 4.5

This article was previously published under Q175372


When you run BackOffice Small Business Server, you may notice that the network is not functioning properly and you may receive an error message.

NOTE: No error message is displayed in Small Business Server 4.0.


If there is no network card installed (or if no network card is detected during setup) when the Small Business Server software is installed, there is no network connectivity. By default, the MS Loopback Adapter is installed. If this occurs, the system functions without a network.


To resolve this problem, remove the MS Loopback Adapter and add a network adapter card listed on the Small Business Server HCL.

To remove the MS Loopback Adapter:

  1. Start the Network tool in Control Panel.
  2. Click the Adapters tab.
  3. Select the MS Loopback Adapter entry and click Remove.

After you have removed the MS Loopback Adapter, follow these steps to add the proper network adapter card installed in the system.

NOTE: The settings specified below are the default settings as configured by the automated Small Business Server setup.

  1. On the Adapters Tab, select Add.
  2. From the list box, select a network adapter and click OK. System will prompt for the Small Business Server/Windows NT compact disc. If the adapter requires a vendor supplied driver, click Have Disk and insert the vendor's disk.
  3. Specify the correct IRQ and base address ranges for the network adapter and click OK. Do not restart if prompted.
  4. Specify the protocols by clicking the Protocols tab and then add TCP/IP. Additional protocols can be added as necessary.
  5. After the protocol has been added, click the IP Address tab and specify the IP address to be the default address of (another address can be specified if necessary).
  6. Leave the default gateway blank.
  7. Specify the subnet mask as
  8. Click the WINS tab and enter as the primary and secondary WINS server addresses.
  9. Click to select the Enable LMHOSTS Lookup check box.
  10. Click OK and restart the computer.


Microsoft has confirmed this to be a problem in BackOffice Small Business Server version 4.0. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.

Additional query words: sbsfaqtop smallbiz SBS connectivity

Keywords: kbbug kbsetup KB175372