The DHCP database can be moved or migrated from a Windows Server 2003 server to a Windows Server 2012R2 server. I will explain how I did this for my network. It took me like 5 minutes to migrate.
To move a DHCP database and configuration from a server that is running Windows Server 2003 to another server that is running Windows Server 2012R2 (or 2008):
1. Log on to the source DHCP server by using an account that is a member of the local Administrators group. Domain Administrator worked for me.
2. Click Start, click Run, type cmd in the Open box, and then click OK.
3. Type “netsh dhcp server export C:\dhcp.txt all” , and then press ENTER.
Note: You must have local administrator permissions to export the data.
Configure the DHCP server service on the server that is running Windows Server 2012R2
1. Click Start, click Administrative Tools, click Server Manager. If needed acknowledge User Account Control.
2. In Roles Summary click Add Roles, click Next, check DHCP server, and then click Next.
Import the DHCP database
1. Log on as a user who is an explicit member of the local Administrators group. A user account in a group that is a member of the local Administrators group will not work. If a local Administrators account does not exist for the domain controller, restart the computer in Directory Services Restore Mode, and use the administrator account to import the database as described later in this section. (For me it worked with Domain Administrator account login in normal startup mode).
2. Copy the exported DHCP database file to the local hard disk of the Windows Server 2012R2.
3. Verify that the DHCP service is started on the Windows Server 2012R2.
4. Click Start, click Run, type cmd in the Open box, and then click OK.
5. At the command prompt, type “netsh dhcp server import c:\dhcp.txt all” , and then press ENTER, where c:\dhcp.txt is the full path and file name of the database file that you copied to the server.
6. Verify that all settings, scopes and clients are imported.
Authorize the DHCP server
1. Click Start, point to All Programs, point to Administrative Tools, and then click DHCP.
Note You must be logged on to the server by using an account that is a member of the Administrators group. In an Active Directory domain, you must be logged on to the server by using an account that is a member of the Enterprise Administrators group.
2. In the console tree of the DHCP snap-in, expand the new DHCP server. If there is a red arrow in the lower-right corner of the server object, the server has not yet been authorized.
3. Right-click the server object, and then click Authorize.
4. After several moments, right-click the server again, and then click Refresh. A green arrow indicates that the DHCP server is authorized.
5. On the old DHCP server (2003), unauthorize the DHCP server if everything went well.
Don’t forget to install another server with DHCP and create a DHCP Failover (Hot Standby or Load Balanced). This is one of the new nifty features since Windows Server 2012.