Server 2003 Tutorials

This tutorial explains how to configure DHCP Server, how to create and activate a DHCP scope and how to authorize a DHCP server in Windows Server 2003 step by step.

The DHCP servers maintain scopes, reservations, and options as set by the administrator.

Scopes

A scope must be properly defined and activated before DHCP clients can use the DHCP server for automatic TCP/IP configuration. A DHCP scope is an administrative collection of IP addresses and TCP/IP configuration parameters that are available for lease to DHCP clients of a specific subnet. The network administrator creates a scope for each subnet.

A scope has the following properties:

  • A scope name, assigned when the scope is created.
  • A range of possible IP addresses from which to include or exclude addresses used in DHCP lease offers.
  • A unique subnet mask, which determines the network ID for an IP address in the scope.
  • Lease duration values.

Each DHCP scope can have a single continuous range of IP addresses. To use several address ranges within a single scope you must first define the entire address range for the scope, and then set exclusion ranges.

Lease Durations

When a scope is created, the lease duration is set to eight days by default. However there are situations when the administrator might want to change the lease duration. The following are examples of adjusting the lease duration due to individual network consideration:

  • An organization has a large number of IP addresses available and configurations that rarely change. The administrator increases the lease duration to reduce the frequency of lease renewal exchanges between clients and the DHCP server. Because the DHCP clients are renewing their leases less frequently, DHCP-related network traffic is reduced.
  • A limited number of IP addresses are available and client configurations change frequently or clients move often in or out of the network. The administrator reduces the lease duration. This increases the rate at which unused addresses are returned to the available address pool for reassignment.

Exclusion Ranges

When you create a new scope, immediately exclude the addresses of existing statically configured computers from the scope. By using exclusion ranges, you can exclude specific IP address ranges within a scope so that those addresses are not offered to clients. Assign IP addresses within exclusion ranges to computers or devices that must have a static IP address, such as servers, firewalls, or routers.

You can use excluded IP addresses on your network by manually configuring these addresses at computers that do not use DHCP to obtain an address, or by configuring reservations for these addresses.

Reservations

You can reserve IP addresses for assignment to specified computers or devices on the network. Reservations ensure that a specified hardware device on a subnet always receives the same IP address lease. Use reservations for DHCP-enabled devices that must always have the same IP address on your network, such as servers that do not support Domain Name System (DNS) dynamic update.

DHCP Options

DHCP options provide clients with additional configuration data, such as specific server addresses, along with an address lease. For example, when the Transmission Control Protocol/Internet Protocol (TCP/ IP) properties of a client computer have been configured to obtain a DNS server address automatically, that computer is relying on DHCP options configured at the DHCP server to acquire a DNS server address (or set of addresses).

Create new scope wizard options

IP Address Range :-
This option allows you to specify the starting and ending IP addresses that define the range of the scope, along with the subnet mask you want to assign to the distributed addresses.

Add Exclusions
This option allows you to specify the IP addresses within the defined range that you do not want to lease to DHCP clients.

Lease Duration
This option allows you to define the lease duration values. These lease durations are then assigned to DHCP clients.

Configure DHCP option
This option allows you to determine whether to configure DHCP options for the scope through subsequent wizard options in the New Scope Wizard or later.

Depending on the selected option here you may see further options. If you select the option to configure DHCP options later, the wizard does not give you an opportunity to activate the scope. You must activate the scope manually before it can begin leasing addresses.

Router (Default Gateway) (optional)
This option allows you to specify which default gateway (and alternates) should be assigned to DHCP clients.

Domain Name And DNS Servers (optional)
This option allows you to specify both the parent domain to be assigned to client computers and the addresses of DNS servers to be assigned to the client.

WINS Servers (optional)
This option allows you to specify the addresses of WINS servers to be assigned to the client. Clients use WINS servers to convert NetBIOS names to IP addresses.

Activate Scope (optional)
This option allows you to determine whether the scope should be activated after the wizard has completed.

Authorizing a DHCP Server

The authorization of DHCP servers was a feature introduced in Windows 2000 and is included with Windows Server 2003. Before a DHCP server that is a member of an Active Directory domain can lease IP addresses to clients on a network, it must be authorized to do so. This prevents a DHCP server with incorrect information from being introduced on the network. For example, a DHCP server with incorrect scope information can't lease providing DHCP clients with incorrect IP parameters. DHCP servers are authorized through the DHCP management console; this process must be performed by a user who is a member of the Enterprise Admins group.

Activating a Scope

After you define and configure a scope, the scope must be activated before the DHCP server can begin providing service to clients. However, you should not activate a new scope until you have specified the DHCP options for it.

Before a DHCP server is fully functional on a network, it must be configured with at least one scope and must be activated. A scope is a range, or pool of IP addresses that can be leased to DHCP clients by the server when requested.

Each scope created consists following information:

  • A range of IP addresses that can be leased to clients.
  • A subnet mask that determines the subnet for the IP address.
  • A scope name that appears in the DHCP management console.
  • The lease duration, which determines when a DHCP client must renew its IP address.
  • Optional parameters, also known as scope options, that need to be assigned to clients, such as the IP address of the DNS server, default gateway, and WINS server.

To create a new scope using the DHCP management console, perform the following steps:

Click Start, point to Administrative Tools, and click DHCP.

dhcp server in administrator tools

Within the DHCP management console, right-click on your DHCP server and click on New Scope option.

new scope

This launches the New Scope Wizard. Click Next to continue.

 new scope welcome

Type in a name and description for the scope that will make it easily identifiable within the management console. Click Next.

new scope name

Enter the range of IP addresses for the scope. Verify the length and subnet mask.

 new scope ip address range

Configure any IP addresses that should be excluded from the scope

291 wz new scope add exclusion

Click Next.

 new scope add exclusion add button

Next, configure the lease duration for the scope. The lease duration determines the length of time till client can use an IP address before it must be renewed. The default value is eight days. Click Next.

 new scope lease duration

At this point, you can configure additional parameters which you want assign the DHCP clients. Select yes and Click on Next to accept the default selection.

291 new scope configure

Router (Default Gateway) window appears. Entrer the IP address of router and click next

new scope router

Domain Name And DNS Servers window appears. In the Parent Domain text box, type your DNS server name and in the IP Address text box, type the IP Address of DNS server and then click Add and click on next

291 wz new scope domain

WINS Servers window appears. Click on Next.

 new scope wins server

Activate Scope window appears. We would activate DHCP server in our next article so select no and Click on Next

 new scope activate later

Completing The New Scope Wizard window appears. Click on Finish.

291 wz new scope finish

The Configure Your Server Wizard indicates that the server is now a DHCP server.

new scope finish server

Now we have configured DHCP server scope with following options

  • Scope name :- LUCKNOW_STUDENT_LAB_1
  • IP Address Range :- 192.168.0.2 to 192.168.0.20
  • Exclusion Range :- 192.168.0.8 to 192.168.0.10 And 192.168.0.12 to 192.168.0.14
  • Lease Duration :- Days 8 hour 0 Minutes 0

This server would not assign any IP address to clients computers yet. Before it start working we need to make it active and authorized . We would do it in next article.

To activate DHCP Server scope

Open DHCP console

dhcp before authorize

Now right click on Scope and click on Activate

 scope activate

Authorization of DHCP server

DHCP servers must be authorized if they are to be integrated in Active Directory networks. Only domain controllers and domain member servers participate in Active Directory, and only these server types can become authorized. When your network includes Active Directory domains, the first DHCP server you install on the network must be an authorized DHCP server. The authorization of DHCP servers was a feature introduced in Windows 2000 and is included with Windows Server 2003. Before a DHCP server that is a member of an Active Directory domain can lease IP addresses to clients on a network, it must be authorized to do so. This prevents a DHCP server with incorrect information from being introduced on the network.

To authorize a DHCP server

Right click on server and click on Authorize

 scope authorize

Now we have activated and authorized DHCP server but it would not show here until we refresh it. Click on refresh

dhcp refresh after authorize

Now DHCP is configured and ready to lease IP. You can see the status in right panel

dhcp server active authorezied

If you need to unauthorized DCHP server you can do it easily by right clicking on server and click on Unauthorized

scope unauthoreize

Now we have configure, activate and authorized DHCP Server.