These are brief instructions. Microsoft has the full-value version, here: How to move a DHCP database from a computer that is running Windows NT Server 4.0, Windows 2000, or Windows Server 2003 to a computer that is running Windows Server 2003. If you're like me, you don't wear a helmet, and you will appreciate my brevity. And actually, I changed a couple things.
One notable difference between me and whoever documents technical procedures for Microsoft is that I work on Earth, for a company, and my implementation must not cause an explosion. We have a bunch of VLANs, managed by Cisco routers, that are configured with the ip helper-address command to ensure DHCP broadcasts are forwarded from clients to the DHCP server. I deviate from Microsoft's generic recommendation for DHCP service migration in this way: I will move one VLAN at a time. This allows me to test things as I go, knowing both servers are handling at least some DHCP scopes, affecting as few clients as possible in the event of catastrophe, and giving myself a clear method for reversing my changes. Also, by adjusting the ip helper-address value on my core routers one VLAN at a time I am able to prevent the new and old DHCP servers from handing out addresses for the same subnet.
I. export the DHCP database from the Windows 2000 Server host
1. stop the DHCP service
command line: net stop dhcpserver
2. compact the DHCP data base
command line: cd c:\winnt\system32\dhcp
command line: jetpack dhcp.mdb temp.mdb
3. export the database
download, install, and run Microsoft's DHCP Database Export Import Tool (dhcpexim.exe)
4. restart the DHCP service
command line: net start dhcpserver
II. import the DHCP database to the new Windows Server 2003 host
1. install the Windows DHCP component
Start > Control Panel > Add or Remove Programs > Add/Remove Windows Comonents > Netwoking Services >
Details >
Dynamic Host Configuration Protocol (DHCP) > OK > Next > Finish
2. import the database file
command line: netsh dhcp server import c:\dhcpdb.txt all
3. authorize this DHCP server
before authorizing:
right-click the server object, then click Authorize
III. point the ip helper-address at the new DHCP server
existing configuration, pointing at the old DHCP server:
in Cisco IOS, use this command: ip helper-address 172.16.12.12
IV. confirm
I set my Vista laptop to retrieve an ip address from a DHCP server and plugged it in to a port on the VLAN we just set up...
have my laptop send a DHCP request on to this subnet...
command line: ipconfig /renew
and confirm on the new DHCP server that this address was handed out by the new server...
V. change DHCP lease duration
If you let Windows DHCP do it's own thing, leases will automatically expire after 8 days. But if you want to speed things up, change the DHCP lease duration to something like 2 hours. At least then you'll know sooner if something's broken.
change DHCP lease duration in Windows 2000 Server:
Start > Programs > Administrative Tools > DHCP >
expand the server node you're interested in > right click the scope whose lease you want to change > Properties > on the 'General' tab, in the 'Lease duration for DHCP clients' box, check 'Limited to:' and specify a time span
VI. turn on DHCP logging
Just in case any clients got left behind, check the DHCP log files for unexpected requests. Do this on the Windows 2000 Server for a couple weeks.
to turn on DHCP logging in Windows 2000 Server:
Start > Programs > Administrative Tools > DHCP >
on the 'General' tab, select 'Enable DHCP audit logging'
Windows 2000 will write DHCP log files, one for each day of the week, to this directory: %systemroot%\system32\dhcp
see also:
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