Ensuring unique hostnames for Windows VMs

Duplicate hostnames occur when there are two or more Windows virtual machines with the same hostname on the same network. This can cause failed workgroup sharing, NetBIOS issues, and connectivity issues.

You may encounter duplicate hostname issues if you create your own VMs (for example, by importing VMs or installing Windows OS from scratch on an empty machine image) and add them to an environment with an automatic network. On an automatic network, Skytap attempts to provide a unique hostname for the VM; without a utility called Skytap Helper, Windows won’t recognize this new hostname.

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Installing Skytap Helper (automatic network)

To ensure that Windows recognizes the unique hostname provided by Skytap, you must install Skytap Helper on your imported or custom-built Windows VMs. When Skytap Helper detects that the hostname has been changed, it forces a reboot so the hostname change can take effect in the OS.

For instructions about adding Skytap Helper to your imported or custom-built VM, see Managing Windows hostnames with Skytap Helper.

Notes

  • Skytap Helper is installed on every template in the Skytap public library. VMs created from Skytap templates shouldn’t have duplicate hostname problems.
  • Skytap Helper can only be installed by administrators.
  • Skytap Helper always runs after DHCP initialization.
  • Skytap Helper doesn’t try to change the hostname if there are multiple DHCP interfaces.
  • Skytap Helper validates the target hostname using reverse DNS lookup and verifies the current machine name. If they don’t match, Skytap Helper tries to change the hostname and reboot:

    • If an interactive user is not logged in, Skytap Helper changes the hostname and reboots automatically.
    • If an interactive user is logged in, Skytap Helper prompts for permission to change the hostname and reboot.

Using your own DNS (manual network)

Skytap Helper uses Skytap automatic DNS. If you are using your own DNS, you must manage unique hostname entries for your VMs. For more information about using a custom DNS, see Manually configuring domain name servers.