DHCP custom options are useful when you are working with software or devices that need a nonstandard DHCP option. DHCP custom options in Address Manager are called pre-defined options in Windows Server 2008/2012 or greater.
A pre-defined option in Windows contains three mandatory fields: name, data type, and code, and one optional field: description. In Address Manager custom options have five mandatory fields:
- Option Code
- Display Name
|Mapping of Address Manager Custom Option Types to Windows Pre-defined Option Types|
|Custom Option Type||Address Manager||Windows Server 2008—2012 or greater|
|IPv4 Address||IPv4 Address||IP Address|
|Unsigned 8-bit Integer||Unsigned Integer 8bit||Byte|
|Unsigned 16-bit Integer||Unsigned Integer 16bit||Word|
|Unsigned 32-bit Integer||Unsigned Integer 32bit||Long|
|Unsigned 64-bit Integer||Unsigned 64-bit Integer (Windows)||Long Integer|
|Signed 8-bit Integer||Signed Integer 8bit||No Equivalent|
|Signed 16-bit Integer||Signed Integer 16bit||No Equivalent|
|Signed 32-bit Integer||Signed Integer 32bit||No Equivalent|
|IPv4 Mask||IPv4 Mask||IP Address|
Pre-defined DHCP Options in Address Manager
Address Manager imports pre-defined option definitions as DHCP Custom Option Definitions. These appear on a configuration’s DHCP Settings tab. Custom option definitions are not subject to reconciliation during re-imports. If you need to modify the option code or option type in Windows while the server is in Read-Only mode, you must delete the custom option definition in Address Manager, and then re-import the data from the Managed Windows server.
In Windows DHCP, if an option is not defined, you must create a new pre-defined option definition for it. After you create the definition, you can assign the option at the server, scope, or reservation levels.
While there are many examples of options that do not exist in Windows DHCP as options, three are of particular interest: 150 (TFTP server), 176 (IP Telephones), and 252 (WPAD).
Assignments of these pre-defined options are imported into Address Manager. As with other options, server-level options are imported at the server level, scope-level options are imported at the network level, and reservation-level options are imported at the DHCP reserved address level.