by Stefan Hellman
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DHCP Redundancy
for Windows Server 2003

Instructions how to do a new installation of DHCP redundancy
if you want to upgrade to version 1.17 from an older installation, read the Upgrade instructions.


INSTALLATION
.Net-framework v.2.0 or higher must be installed on the second server.
DHCP-Redundancy v1.17 can only be installed on English or Swedish version of 2003 Server

1. Download DHCP-Redanducy.zip with the link at the top of this page.

2. Create the directory c:\DHCP-Redundancy on the second server and unzip the files there.

3. Install the DHCP service on the second server, dont create any scopes. You may have to Authorize the DHCP service.

4. Go to Computer Management and stop the DHCP Server service.

5. Copy the file DHCP-Backup.bat to your main server. This .bat file extracts the info from the main DHCP service that will be imported into the second service.

6. On your main server create a scheduled task that should be run every day preferably at night, eg. 01.00. Choose to run DHCP-Backup.bat and add the name (or IP) of your second server, eg. "DHCP-Backup.bat Server2". The user account that shall run the task must have rights to write a file in the directory c:\DHCP-Redundancy on the second server.

7. Right-click on the task and choose Run. Within a minute it should have created the file DHCP-Backup.txt in the c:\DHCP-Redundancy on the second server.

8. Switch to the second server. The file DHCP-Redundancy.ini holds the settings for the service, dont edit this file manually. Instead run the program DHCP-Redundancy-config.exe.

9. In the box "Mail address of alert receivers" enter an email address of a person that shall receive an email when the service switches over to the second DHCP service. Then click Add. You can have up to 100 mail receivers

10. In the box "Mail address of alert sender" enter an email address that the service will use as the sender address for the alert emails.

11. Click the checkbox if you want the redundancy service to send an alert mail also when the main dhcp service is restored and the second is stopped.

12. Enter the IP address of the mail server and the main DHCP server.

13. Enter a time of synchronization when the second DHCP server should import the exported backup of the main server. It should be 5-10 minutes after the configured time for the scheduled task you set up earlier.

14. Now test the email settings by clicking the Send button. If everything is ok the emails should arrive shortly.

15. Click Save to save the settings to DHCP-Backup.ini and exit the program.

16. Install the redundancy service on the second server with the .Net command InstallUtil.exe, syntax eg. C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\InstallUtil.exe c:\DHCP-Redundancy\DHCP-Redundancy-service.exe.

17. Open Computer Management, the service DHCP-Redundancy should have been created. Click on it and choose Run to start it. After one minute the service starts to import the DHCP backup to the second server, it will take a few minutes. When the backup is imported it renames the file DHCP-Backup.txt to DHCP-Backup.old.

18. When the file is renamed, go to Computer Management and start the DHCP service. Open the DHCP tool and check that everything looks fine, that it is a replica of your main DHCP service. Stop the DHCP service again. The servers are now ready.

19. If your client computers are not on the same subnet as your servers, then configure your router and add a DHCP relay address to the second server.

20. I recommend that you go to Properties on your both DHCP servers in the DHCP management tool and choose the Advanced tab and set the Conflict Detection Attempts to 2.

All installation is now done.

Now check that everything works as it should. On the main DHCP server, open Computer management and stop the DHCP service, within one minute the second DHCP service should start and the alert receivers should receive an alert email. You should be able to renew the ip address on your clients, now provided by the second server. Now start the main DHCP service and within one minute the second service should stop.

Direct questions and tell us your experience about DHCP Redundancy service at DHCP Redundancy Forum at the top of this page.