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Migrated DHCP Server and getting old DNS server

When migrating a DHCP server over it is very important to make sure your old DNS servers are not being used by your servers and computers.

1. Performing “ipconfig /all” yields the following incorrect result; and really should say 192.168.2.84 in our case.  By checking the other fields we know this is not a static ip and does not contain any static dns entries.. so what is going on here?

  • 192.168.2.250 = old dns
  • 192.168.2.20 = old dns

wrong-old-dns-servers

2. Go into DHCP and navigate down to your scope.  Right click on “Server Options and select “Configure Options”

dns-servers-wrong-dhcp

3. Then add the correct DNS Servers to the configuration.  You can even remove the old DNS servers if desired.  (In my example I did not remove the DNS Servers).

add-correct-dns-servers-dhcp

4. If we go back onto our client and peform the following commands we will see the updated DNS information as follows

  • via cmd prompt “ipconfig /flushdns”
  • via cmd prompt “ipconfig /release”
  • via cmd prompt “ipconfig /renew”

computer-has-correct-dns-servers-listed

Success!