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windows server - how to change a subnet mask of a dhcp scope

 windows server - how to change a subnet mask of a dhcp scope



for example change subnet mask from a scope 172.16.0.0/16 to 172.16.99.0/24



1) export to xml file using powershell

      Export-DhcpServer -Computername <name of computer> -Leases -File C:\export_dhcpserver.xml -verbose



      <name of computer could be 127.0.0.1 or localhost if do export the configuration directly from the server>

	  

2) make a copy of the exported file, name it: import_dhcpserver.xml



3) edit the import_dhcpserver.xml file and replace the dhcp scope section,

   and all lease entries that reference to the section name:

   

   3.1) dhcp scope section, change the ScopeId + the subnet mask

     <Scopes>

     <Scope>

         <ScopeId>172.16.99.0</ScopeId>

         <Name>intern</Name>

         <SubnetMask>255.255.255.0</SubnetMask>			#change subnet mask here

         <StartRange>172.16.99.1</StartRange>

		

		

   3.2) dhcp lease entrie, make sure to change the ScopeId to the new scope id

         <Lease>

       <IPAddress>172.16.99.177</IPAddress>

       <ScopeId>172.16.99.0</ScopeId>				#change the scope ip here

			

			

4) delete the scope id(s) from the dhcp server, using the dhcp admin tool



5) now import the new file:

    Import-DhcpServer -Computername <name of computer> -Leases -File C:\import_dhcpserver.xml -BackupPath C:\dhcpbackup\ -Verbose





6) Restart both DHCP client and Server services



7) check the dhcp tool if everything looks fine

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windows server - how to change a subnet mask of a dhcp scope