How DHCP Server Scope and Reserved Client Options Are Applied

DHCP Server i

Windows 98

File and Print Server

Scope A

Scope A

Scope B

Router

Scope B

Windows XP

Windows XP

ILLEGAL FOR NON-TRAINER USE

Why use levels of DHCP DHCP applies options to client computers in a specific order: options?

1. Server level

2. Scope level

3. Class level

4. Reserved client level

How DHCP options are applied

As a result, you can define DHCP-assigned options with varying levels of authority so that certain options take precedence over other options.

How options are applied relates directly to where they are configured. The following table describes the levels of DHCP options and their precedence.

DHCP option

Precedence

Server-level option Scope-level option Class-level option Reserved client-level option

A server-level option is assigned to all DHCP clients of the DHCP server.

A scope-level option is assigned to all clients of a scope.

A class-level option is assigned to all clients that identify themselves as members of a class.

A reservation-level option is assigned to one DHCP client.

For example, the server option makes the largest impact (by affecting all clients that the DHCP server supports), while the reserved client-level option makes the least amount of impact (by affecting only one client that the DHCP server supports).

If you create a reservation for a specific computer, you can assign a reserved client-level option that will then apply only to that reservation. By using reservations and reserved client-level options, you can map specific options to specific computers.

Example Referring to the first example in the slide, the DHCP server-level option has been applied to both Scope A and Scope B, in addition to the DHCP server, Scope B's File and Print server, and all clients.

In the second example, the DHCP scope-level option has been applied to Scope B, in addition to Scope B's File and Print server and the Windows XP client.

In the third example, the DHCP reserved client-level option has been applied only to the File and Print server.

Additional examples The following three examples each use a server, scope, or reserved client-level option.

■ By using an option at the server level, you can configure all clients to use the same DNS server or WINS server. For example, you may have only one DNS server or WINS server for a large number of client computers and want to configure the option only once. If you configure a server-level option, all scopes and reservations inherit this option. As a result, you can configure servers once for multiple uses.

■ By using an option at the scope level, you can define a unique router address for each scope, when each subnet requires a unique scope. For example, it is common to create one scope per physical subnet. If you create one scope per physical subnet, then each subnet will have at least one unique router value.

■ By using an option at the reserved client level, you can configure a specified DHCP client to use a specific router to access resources outside the client's subnet You might want to create a reserved client-level option of a dedicated router for a computer that always needs to test access across the router.

How DHCP Class-level Options Are Applied

ILLEGAL FOR NON-TRAINER USE

How DHCP class-level options are applied

Why use class-level options?

Types of class-level options

Vendor classes

ILLEGAL FOR NON-TRAINER USE

Class options are added on to the server, scope, or reserved client-level option. Their settings are applied to a subset of DHCP clients that match the class ID.

Class-level options are most often used either to override or to augment standard DHCP option values that are set at either the server, scope, or reserved client level.

Class-level options apply to any DHCP client that identifies itself as a member of the class. You can use vendor- and user-class options to provide unique configurations to specific types of client computers.

■ Vendor-class is an administrative feature that allows DHCP clients to be identified and leased according to their vendor and hardware configuration types.

■ User-class is an administrative feature that allows DHCP clients to be grouped logically according to a shared or common identifier.

Vendor-class options identify the vendor type of a DHCP client's operating system and its configuration, and provide unique options that are only applicable to the specified vendor class. You can configure vendor class options to manage DHCP options that are specific to the vendor type and are assigned to clients of that vendor type. Vendor options are not used to configure standard TCP/IP options, but rather to configure options specific to the vendor type.

You can also define additional vendor identifiers on the DHCP server if they are provided in the vendor's DHCP client software. Before you configure additional vendor-class options, you must determine which identifier, if any, a specific vendor uses; you can do this by contacting the vendor of the client operating system or network software. The administrator cannot add vendor identifiers on the DHCP client; vendor identifiers are written into the TCP/IP protocol program code.

Examples of vendor The three default vendor identifiers in a DHCP server running Windows Server classes 2003 are:

■ Microsoft Windows 2000 Options

■ Microsoft Windows 98 Options

■ Microsoft Options

For example, one of the vendor class options that is supported by Windows 2000 and later is Microsoft Disable NetBIOS Option which disables network basic input/output system (NetBIOS) over TCP/IP. Enabling this option would disable network basic input/output system (NetBIOS) over TCP/IP for all Windows 2000 or later clients on the scope or server on which the option is defined.

User classes User-class options provide a property that assists a DHCP server in identifying a DHCP client that belongs to a specified group. You assign user class options to a client based on an identifier, and the client sends this identifier to the DHCP server to identify itself.

You configure user class options to manage DHCP options that you want to assign to clients that require a common configuration.

Examples of user A user-class option could be configured to identify a group of computers (such classes as kiosks, notebooks, or the computers in a computer lab). For example: you can configure user-class options to provide a shorter lease time for notebooks that are dial-in clients, to return the addresses to the IP address lease pool more quickly.

There are two default user-class identifiers that are configured on DHCP clients running Windows Server2003.

■ Default Routing and Remote Access Class

■ Default BOOTP Client Class

These classes cannot be deleted or modified.

Note For more information about configuring class-based options, see the Windows Server 2003 resource kit.

How to Configure DHCP Options

Your instructor will demonstrate how to:

Configure a DHCP server option

* Configure a DHCP scope option

*************************** **illegal for non-trainer use* *****************************

Introduction After configuring a DHCP scope, the next task is to configure DHCP options.

You can either configure DHCP options while you are configuring a DHCP scope, or at a later time after configuring a DHCP scope.

Note It is recommended that you log on with an account that has nonadministrative credentials and use the Run as command with a user account that has appropriate administrative credentials to perform this task.

Procedure for configuring DHCP server options

To configure a DHCP server option:

1. Open the DHCP console.

2. In the console tree, under the server name, click Server Options.

3. On the Action menu, click Configure Options.

4. In the Server Options dialog box, in the list of Available Options, select the option that you want to configure.

5. Under Data entry, complete the information that is required to configure this option.

6. In the Server Options dialog box, click OK.

Procedure for To configure a DHCP scope option:

configuring DHCP scope options 1. Open the DHCP console, and, under the appropriate scope, click Scope

Options.

2. On the Action menu, click Configure Options.

3. In the Scope Options dialog box, in the list of Available Options, select the option that you want to configure.

4. Under Data entry, complete the information that is required to configure this option.

5. In the Scope Options dialog box, click OK.

Practice: Configuring DHCP Options

ILLEGAL FOR NON-TRAINER USE In this practice, you will configure DHCP options.

Objectives Instructions

Scenario

Practice

ILLEGAL FOR NON-TRAINER USE In this practice, you will configure DHCP options.

To complete this practice, refer to the Implementation Plan Values document, located in the Appendix at the end of your student workbook.

You must be logged on with an account that has non-administrative credentials and use the Run as command with a user account that has appropriate administrative credentials to complete the task.

The Lab department has just received a new DNS server for testing. The systems engineer has asked that any new scopes that are configured on the DHCP server for the Lab department use this new DNS server as the DNS option. In addition, the Lab scope needs to reflect the addition of two new WINS servers that were added to the Lab department. You will configure these options on the DHCP server.

► Configure DHCP options at the scope level

■ Complete this task from both student computers.

■ Option IP address: the IP address of your Partner Network Connection

► Obtain the DHCP scope option

■ Complete this task from the higher number student computer.

1. Use the ipconfig /renew command to obtain an IP address from the DHCP server.

2. Using the ipconfig /all command, verify that the default gateway IP address for the Partner Network Connection is the IP address of the DHCP server's Partner Network Connection.

+1 0

Responses

  • Chica
    How is a client is to a specific reservation in the dns server scope?
    6 years ago
  • haddas
    How to configure scopelevel option for dhcp server and show the consoles?
    6 years ago
  • LEONE ESPOSITO
    How to set DHCP class ID information at a client computer via GPO?
    6 years ago
  • Angelica Banks
    How to see what dhcp options are applied?
    6 years ago
  • kevin
    How dhcpserver scope and reservedclient options are applied?
    6 years ago
  • olli
    How to create the multiple scope in dhcp with appropriate server option?
    6 years ago
  • demsas
    What does the set access scope option do when applied to a dhcp scope?
    11 months ago
  • beatrice
    How to chek if dhcp option are applied?
    10 months ago
  • dalia
    Which dhcp option takes precedence?
    5 months ago
  • terttu
    When are DHCP options applied on client?
    4 months ago

Post a comment