Troubleshooting Host IDs in ISA Server 2004 Enterprise Edition

During installation, Microsoft® Internet Security and Acceleration (ISA) Server 2004 Enterprise Edition assigns a persistent, unique host ID (in the range of 2–32) to each server in an array during Setup. Note that an array does not support more than 31 servers.

This host ID is used to uniquely identify the server in storage, for virtual private network (VPN) settings, and for Network Load Balancing (NLB) configuration.

Host ID Allocation Conflicts

Resolving Host ID Conflicts

Host ID Allocation Conflicts

The following describes how a host ID is allocated, and situations where conflicts can occur.

Unattended Setup

If you run unattended Setup, you can specify a HostID property. If no value is specified, a host ID is automatically assigned to the server.

If an invalid host ID value is specified in the .ini file during unattended Setup, or there is a conflict in the automatically allocated host ID, Setup will complete but the Firewall service will not start and an alert will be generated. Check the Event Viewer for more information.


In some export/import configurations, a host ID may be automatically generated during the export. If this host ID causes a conflict during the import, the import will succeed but the Firewall service will not start, and an alert will be generated. After the import, check the Event Viewer for more information.

Resolving Host ID conflicts

The host ID value should not be changed, unless an alert is issued in the Event Viewer indicating that a conflict has occurred in host ID assignment. In these circumstances, modify the host ID for a server as follows:

  1. In the console tree of ISA Server Management, expand the array node, click Configuration, and then click Servers.
  2. In the details pane, right-click the required server, and then click Properties.
  3. In Host ID, click the drop-down list and select one of the unallocated host IDs.
  4. Click OK, and in the details pane of ISA Server Management, click Apply to apply the change.


   If the Firewall service did not start, and you have modified the host ID to resolve a host ID conflict, manually restart the Firewall service after modifying the host ID and applying the change