Windows DHCP Custom Options - BlueCat Address Manager - 9.0.0

Address Manager Administration Guide

BlueCat Address Manager

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
  • Name
  • Display Name
  • Description
  • Type
Custom option types are named differently in Address Manager and on Windows. The following table shows the custom option equivalents across the two systems.
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
Text Text String
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
Boolean Boolean No equivalent
IPv4 Mask IPv4 Mask IP Address
String String No equivalent
Binary Binary (Windows) Binary
Encapsulated Encapsulated (Windows) Encapsulated

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).

In Address Manager these options are used frequently, so they have been built into the system and are available for assignment as DHCP client deployment options. Because these option codes already exist in Address Manager, you cannot create new custom option definitions for them in the Address Manager user interface, and you cannot import them into Address Manager as new custom option definitions. However, although the definitions are ignored during import, assignments of these pre-defined options (server, scope or reservation levels) are included as part of the import.
Note: If a deployment to a Read-Write server includes options 150, 176, or 252, the Address Manager name for the option definition overwrites the pre-defined option definition name in Windows.

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.

You create DHCP custom option definitions from a configuration’s DHCP Settings tab. After you create a custom option definition, it is available as a DHCP client option.
Note: Option assignments that have invalid values because they have custom definitions with an incompatible type are ignored (and logged).