Two improvements have been made to the
functionality of DHCP in Windows Server 2008 R2. These improvements
allow for an increased level of functionality beyond the major
improvements made in Windows 2000, Windows Server 2003, and Windows
Server 2008. Even though there are new improvements, the architecture
and design decisions that might have been made in previous Windows
Server versions will still remain valid, but the new functionality will
enhance these best-practice designs.
Automating DHCP Database Backup and Restore
The
process of backing up all DHCP settings and restoring them onto the
same (or a different) server has been streamlined in Windows Server 2008
R2. No longer do administrators need to export Registry keys and
manually move databases between servers or use the DHCP import/export
tool from Microsoft to migrate DHCP. The backup and restore process can
be accomplished directly from the MMC, and the migration of DHCP server
data can be performed using tools included with the Windows Server 2008
R2 operating system.
The DHCP Server service on
Windows Server 2008 R2 will back itself up automatically each hour to
the %systemroot%\system32\dhcp\backup. Of course, only the most recent
backup is maintained in this folder; if historic backup is required, an
administrator should enable Volume Shadow Copy on the drive that
contains the system root and also perform periodic backups of the DHCP
server using Windows Backup or another backup solution, such as
Microsoft Data Protection Manager. When a DHCP administrator is going to
make changes to a DHCP server, it is a best practice to manually
perform a backup of the DHCP database and configuration by performing
the following steps:
1. | Open
the DHCP management console (Start, All Programs, Administrative Tools,
DHCP). If prompted, click Continue to confirm the action.
| 2. | Right-click the server name and choose Backup, as illustrated in Figure 1.
| 3. | Specify a location for the backup file, and click OK. The backup files will then be saved into the location you chose.
|
To
restore a previously backed up DHCP server configuration and database
to the same or an alternate server, perform the following steps:
1. | Open
the DHCP management console on the server to which you want to restore
the scope (Start, All Programs, Administrative Tools, DHCP). If
prompted, click Continue to confirm the action.
| 2. | Right-click the server name and choose Restore. Select the location where the backup files can be found, and click OK.
| 3. | When
you see a dialog box asking whether the service can be stopped and
restarted, click Yes to continue. The service will be restarted, and the
entire database and Registry will be restored.
|
Note
The DHCP backup and restore
process is extremely useful in migrating existing DHCP server
configurations, scopes, and up-to-date lease information to new DHCP
servers. However, because down-level (pre–Windows Server 2008 R2) DHCP
servers do not support automatic backup and restore, you will need to
migrate from these servers by either the DHCP import/export tool between
Windows 2003 systems or the Windows Server Migration Tools can be used
to migrate the Windows Server 2003 DHCP server configuration and
database to a Windows Server 2008 R2 system.
Migrating DHCP Servers Using Windows Server Migration Tools
Windows Server 2008 R2
includes a new set of PowerShell cmdlets called the Windows Server
Migration Tools. These tools can be installed on a Windows Server 2008
R2 system from the Add Features Wizard in Server Manager. The Windows
Server Migration Tools can be used to migrate services between source
servers running Windows Server 2003, Windows Server 2008, and Windows
Server 2008 R2 to destination Windows Server 2008 R2 systems. DHCP is
one of the services that can be migrated with these tools. One of the
major advantages of this tool is the fact that it will migrate not only
scope information, but it will also migrate the existing leases on the
source server scope.
Before the Windows
Server Migration Tools can be used to migrate DHCP services from one
server to another, the tools will need to be installed on both the
source and destination servers. Because the Windows Server Migration
Tools are included with Windows Server 2008 R2, the tool must be
packaged and installed on Windows Server 2003 or Windows Server 2008
systems if the source servers are running either of these operating
systems. The overall process of using the Windows Server Migration Tools
to migrate DHCP services is as follows:
1. | Verify
that the DHCP server settings, scopes, and scope options on the source
DHCP server are the desired settings to migrate, and adjust as
necessary.
| 2. | Install the Windows Server Migration Tools on a Windows Server 2008 R2 system.
| 3. | Create
a deployment folder for the correct operating system (Windows Server
2003 or Windows Server 2008) and platform (x86 or amd64) from a command
prompt on the Windows Server 2008 R2 system with the Window Server
Migration Tools installed.
| 4. | Install
or verify that the Windows Server Migration Tools prerequisites are
installed on the source and destination servers, which include the
latest Windows PowerShell for the specific operating system and
platform.
| 5. | Install the Windows Server Migration Tools package on the desired source and destination DHCP servers.
| 6. | Run
the Windows Server Migration Tools export cmdlet, locally, on the
source DHCP server and copy the export files to the destination DHCP
server.
| 7. | Unauthorize the source DHCP server and change the IP address or remove the system from the network permanently.
| 8. | Add the original source DHCP server IP address to the destination server as a primary IPv4 address on a network adapter.
| 9. | Run the Windows Server Migration Tools import cmdlet, locally, on the destination DHCP server.
| 10. | Enable the DHCP Server service, start it, and verify the imported settings.
| 11. | Authorize the DHCP server.
|
Installing the Windows Server Migration Tools on Windows Server 2008 R2
Before the Windows
Server Migration Tools can be used to migrate DHCP services between
servers, it must be installed on a Windows Server 2008 R2 system. To
install the Windows Server Migration Tools, perform the following steps:
1. | Choose
Start, All Programs, Administrative Tools, Server Manager. In the
console tree, right-click on Features and then click Add Features to
start the Add Features Wizard.
| 2. | On
the Select Features page, scroll down the list of features and select
the check box next to Windows Server Migration Tools; then click Next to
continue.
| 3. | On the Confirm Installation Selections page, click Install to begin installing the Windows Server Migration Tools.
| 4. | On the Installation Results page, review the results and click Close to complete the installation.
|
Creating the Deployment Folder Package of the Windows Server Migration Tools for Down-Level Operating System Installation
When DHCP services will be
migrated to a Windows Server 2008 R2 DHCP server from a source Windows
Server 2003 or Windows Server 2008 system, the Windows Server Migration
Tools will need to be packaged for deployment and installation on those
down-level operating systems. To build the deployment folder package,
perform the following steps:
1. | Using
an account with administrator permissions, log on to the Windows Server
2008 R2 system that has the Windows Server Migration Tools installed.
| 2. | Open
an elevated command prompt by clicking Start, All Programs,
Accessories; locate and right-click Command Prompt and choose Run As
Administrator. If prompted for confirmation, click Continue.
| 3. | In the Command Prompt window, change the directory to %systemroot%\system32\ServerMigrationTools.
| 4. | Type the command SmigDeploy.exe /package /architecture x86 /os ws03 /path c:\downloads
and press Enter. This command creates the installation package for a
Windows Server 2003 x86 system and places the files in the
c:\downloads\SMT_ws03_x86 folder. If the downloads folder is not already
created, the command creates it automatically.
| 5. | Type the command SmigDeploy.exe /package /architecture amd64 /os ws08 /path c:\downloads
and press Enter. This command creates the installation package for a
Windows Server 2008 x64 system and places the files in the
c:\downloads\SMT_ws08_amd64 folder. If the downloads folder is not
already created, the command creates it automatically.
| 6. | Repeat the last command for any additional operating systems that will be used as either source or destination DHCP servers.
| 7. | Close the command prompt and, if necessary, share the c:\downloads folder so that it can be accessed across the network.
|
Installing the Windows Server Migration Tools on Windows Server 2003 DHCP Server
Before the Windows Server
Migration Tools can be installed on a Windows Server 2003 system, the
.NET Framework 2.0 must be installed as well as the latest Windows
PowerShell. Download and install these two prerequisites and also
download any security updates for these add-ons. Once those steps are
completed, perform the following steps before the Windows Server
Migration Tools can be used:
1. | Using an account with administrator permissions, log on to the Windows Server 2003 x86 DHCP server.
| 2. | Click Start and select Run.
| 3. | Type
in the location where the Server Migration Tools package for this
operating system is stored (for this example, \\server20\downloads\).
| 4. | Locate the “SMT_ws03_x86” folder that was created previously, right-click the folder, and choose Copy.
| 5. | Click Start and select Run.
| 6. | Type c:\ and click OK.
| 7. | On
the root of the C: drive, right-click on a blank space and click Paste
to create the c:\SMT_ws03_x86 folder on the Windows Server 2003 system.
Close the window.
| 8. | Click Start and select Run.
| 9. | Type cmd and click OK to open a command prompt.
| 10. | In the Command Prompt window, change the directory to c:\SMT_ws03_x86\.
| 11. | Type SmigDeploy.exe and press Enter to register the Windows Server Migration Tools cmdlets into Windows PowerShell.
| 12. | After the command completes, the original Command Prompt window will be open, as well as a separate PowerShell window. Type exit in each of the Command Prompt windows to close them.
|
The
Windows Server Migration Tools are now installed and registered with
Windows PowerShell on the Windows Server 2003 x86 system and can be used
in a PowerShell window.
Installing the Windows Server Migration Tools on Windows Server 2008 64-Bit Edition DHCP Server
Before the Windows
Server Migration Tools can be installed on a Windows Server 2008 64-bit
system, install Windows PowerShell from the Add Features link in Server
Manager if it is not already installed. Once Windows PowerShell is
installed, perform the following steps before the Windows Server
Migration Tools can be used:
1. | Using an account with administrator permissions, log on to the Windows Server 2008 64-bit DHCP server.
| 2. | Click
Start. In the search pane, enter the path to the location where the
Server Migration Tools package for this operating system is stored and
press Enter (for this example, \\server20\downloads\).
| 3. | Locate the “SMT_ws08_amd64” folder that was created previously, right-click the folder, and choose Copy.
| 4. | Click Start. In the search pane, type c:\ and press Enter.
| 5. | On
the root of the C: drive, right-click on a blank space and click Paste
to create the c:\SMT_ws08_amd64 folder on the Windows Server 2008
system. Close the window.
| 6. | Click Start, and in the search pane, type cmd.
When the command prompt is listed, right-click the shortcut and choose
Run As Administrator. If prompted, click Continue to open an elevated
Command Prompt window.
| 7. | In the Command Prompt window, change the directory to c:\SMT_ws08_amd64\.
| 8. | Type SmigDeploy.exe and press Enter to register the Windows Server Migration Tools cmdlets into Windows PowerShell.
| 9. | After the command completes, the original Command Prompt window will be open, as well as a separate PowerShell window. Type exit in each of the Command Prompt windows to close them.
|
The Windows Server Migration
Tools are now installed and registered with Windows PowerShell on the
Windows Server 2008 64-bit and can be used in a PowerShell window.
Migrating DHCP Services from Windows Server 2003 x86 to Windows Server 2008 R2
The proceeding steps can be
used to migrate DHCP services from a Windows Server 2003 x86 DHCP server
to a Windows Server 2008 R2 system. Migrating the DHCP services
includes several steps, which are outlined in the following sections.
Exporting DHCP Servers Setting from a Windows Server 2003 DHCP Server
Exporting
the DHCP server settings and scopes must be performed on the source
DHCP server. Before this task can be performed, the .NET framework,
Windows PowerShell, and the Server Migration Tools need to be installed.
Once these tools are installed, follow these steps to export the DHCP
settings from a Windows Server 2003 x86-based system.
1. | Using
an account with administrator permissions, log on to the Windows Server
2003 x86 DHCP server that has the Windows Server Migration Tools
installed and registered with Windows PowerShell.
| 2. | Click Start, click All Programs, click Administrative Tools, and select DHCP.
| 3. | In the DHCP Server console, select and expand the DHCP server. Right-click the DHCP server, and select Properties.
| 4. | In
the DHCP Server Properties window, select the Advanced tab and click
the Bindings button. Note the IP address the DHCP server is using
because we will need this IP address later during the import process on
the destination DHCP server. Close the DHCP Server Properties window.
| 5. | In the DHCP Server console, select and expand the DHCP server. Right-click the DHCP server and select Backup.
| 6. | Select the backup location and click OK to perform the backup.
| 7. | In
the DHCP console window, right-click the DHCP server, select All Tasks,
and select Stop to stop the DHCP Server service. Close the DHCP console
window.
| 8. | Click
Start, click All Programs, click Administrative Tools, click Windows
Server Migration Tools, and click the PowerShell shortcut for Windows
Server Migration Tools. When the PowerShell window opens, it should
default to the c:\SMT_ws03_x86\ folder.
| 9. | In the PowerShell window, type .\Servermigration.psc1 and press Enter to open a separate PowerShell window with the Windows Server Migration Tools module loaded.
| 10. | In the PowerShell window, type the command Export-SmigServerSetting –FeatureID DHCP and press Enter.
| 11. | When prompted for the path, enter c:\DHCPExport and press Enter.
| 12. | When
prompted for a password that will be used to secure the exported data,
enter a password that is six characters or longer and press Enter to
export the settings. Please note this password as it will be used to
import the settings.
| 13. | Close any open Command Prompt and PowerShell windows.
| 14. | Copy the exported folder to the C:\ drive on the destination DHCP server.
| 15. | Change the IP address of the server or remove it from the network permanently.
|
The original DHCP server IP
address will be added to the destination server to ensure full
functionality after the migration. The IP address change is required to
ensure that clients with existing leases will be able to contact the
DHCP server by the original DHCP server IP address. If this step is not
performed, most clients will fail a DHCP renew and may need to have help
desk staff assist with an Ipconfig /release and Ipconfig /renew on each
machine that fails a DHCP renew.
Importing DHCP Server Settings to a Windows Server 2008 R2 DHCP Server
To
import the previously exported Windows Server 2003 x86 DHCP server
settings, install the Windows Server Migration Tools from the Add
Feature link in Server Manager. Windows PowerShell is already installed
on a Windows Server 2008 R2 system so this task is not necessary. The
DHCP import function will overwrite all DHCP settings if imported onto
an existing DHCP server, so it is a best practice to not install the
DHCP Server role before running the import. To import the DHCP server
settings and information from the original Windows Server 2003 system,
perform the following steps:
1. | Using
an account with administrator permissions, log on to the Windows Server
2008 R2 system that has the Windows Server Migration Tools installed.
| 2. | Open
an elevated command prompt by clicking Start, All Programs,
Accessories; locate and right-click on Command Prompt and choose Run As
Administrator. If prompted for confirmation, click Continue.
| 3. | Ping the original IP address of the Windows Server 2003 DHCP server to ensure that it is no longer in use.
| 4. | Click
Start, click All Programs, click Administrative Tools, click Windows
Server Migration Tools, and click the PowerShell shortcut for Windows
Server Migration Tools.
| 5. | In the PowerShell window, type the command Import-SmigServerSettings –FeatureID DHCP –Verbose and press Enter.
| 6. | When prompted for the path, type c:\DHCPexport and press Enter.
| 7. | When
prompted, enter the password used to secure the exported DHCP settings
and press Enter. If the DHCP service had been installed previously, this
import will fail. If the import failed due to the DHCP role being
previously installed, the –Force option can be appended to the command;
however, all existing DHCP server settings will be overwritten.
| 8. | Once the import completes and reports successful, type exit and press Enter to close the Windows PowerShell window.
| 9. | Click Start, click All Programs, click Administrative Tools, and select Services.
| 10. | Scroll down in the left pane to locate the DHCP Server service, right-click the service, and choose Properties.
| 11. | Change the DHCP Server service startup to Automatic and click OK to save the settings.
| 12. | Right-click the DHCP Server service and select Start to start the service and then close the Services console window.
| 13. | Click Start, click All Programs, click Administrative Tools, and select DHCP.
| 14. | In
the DHCP console window, the local server should be listed, expand the
server, and expand the IPv4 node to reveal the imported scope. Review
the scope settings, leases, and other information.
| 15. | In the console pane, right-click the IPv4 node and select Properties.
| 16. | Select
the Advanced tab and click the Bindings button. Verify that the
original DHCP server IP address is listed and checked. Click OK to close
the Bindings window and click OK again to close the IPv4 Properties
window.
| 17. | In the console pane, right-click the local server node and select Authorize.
| 18. | Refresh the window and verify the server is operational.
| 19. | In the console pane, right-click DHCP at the top and select Manage Authorized Servers.
| 20. | If the original server is listed, select it and click Unauthorize.
| 21. | Verify that a new lease can be obtained and close the DHCP console.
|
This completes the DHCP server migration process.
Understanding DHCP Client Alternate Network Capability
The DHCP client that is
included in client systems running Windows 7, Windows Vista, Windows XP,
and Windows 2000 can have a static IP address assigned to clients when a
DHCP server is unavailable. This static IP address takes the place of
the APIPA address that would normally be configured in these cases.
Note
If the Registry key to disable APIPA has been created, it will also disable the alternate IP configuration settings.
This type of
functionality could be used on remote network systems that run into
issues with DHCP Relay Agents not responding in a timely fashion. This
setting should be used with extreme caution as a machine that is taken
to a foreign network without a DHCP server might end up adding itself to
the network with an IP address that is already in use. If the network
administrator wants to configure this setting, the following steps can
be executed on a Windows 7 client as an example:
1. | Click Start and select Control Panel.
| 2. | Click on Network and Internet.
| 3. | Click on View Network Status and Tasks.
| 4. | Click on Change Adapter Settings in the left pane.
| 5. | Right-click
the adapter in question, and choose Properties. If prompted for
authorization, enter the credentials, if required, and click Yes or
click Continue.
| 6. | Select Internet Protocol Version 4 (TCP/IPv4) and choose Properties.
| 7. | Select the Alternate Configuration tab.
| 8. | Select the User Configured option button, enter the appropriate static IP information, and click OK.
| 9. | Click the Close button to close the property page.
|
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