Creating Scopes

You must use DHCP Manager to create, manage, or remove scopes.

To create a new DHCP scope

1. In the DHCP Servers list in the DHCP Manager window, select the server for which you want to create a scope.
2. From the Scope menu, choose Create.

3. To define the available range of IP addresses for this scope, type the beginning and ending IP addresses for the range in the Start Address and End Address boxes.

The IP address range includes the Start and End values. This range should not include addresses of existing statically configured machines. Either these static addresses should be outside the range for the scope or they should be immediately excluded from the range. Because the DHCP server itself is statically configured, be sure that its IP address is outside of, or excluded from, the range of the scope.

Note You must supply this information before this scope can be activated.

4. In the Subnet Mask box, DHCP Manager proposes a subnet mask, based on the IP address of the Start and End addresses. Accept the proposed value, unless you know that a different value is required.
5. To define excluded addresses within the IP address pool range, use the Exclusion Range controls, as follows:
   • Type the first IP address that is part of the excluded range in the Start Address box, and then type the last number in the End Address box. Then choose the Add button. Continue to define any other excluded ranges in the same way.
   • To exclude a single IP address, type the number in the Start Address box. Leave the End Address box empty, and then choose the Add button.
   • To remove an IP address or range from the excluded range, select it in the Excluded Addresses box, and then choose the Remove button.

The excluded ranges should include all IP addresses that you assigned manually to other DHCP servers, non-DHCP clients, diskless workstations, or RAS and PPP clients.

6. To specify the lease duration for IP addresses in this scope, select Limited To. Then type values defining the number of days, hours, and seconds for the length of the address lease.

If you do not want IP address leases in this scope to expire, select the Unlimited option. As noted in "Guidelines for Lease Options" later in this chapter, infinite leases should be used with great caution.

7. In the Name box, type a scope name.

The scope name is any name you want to use to describe this subnet. The name can include any combination of letters, numbers, and hyphens. Blank spaces and underscore characters are also allowed.

Note You cannot use Unicode characters.

8. Optionally, in the Comment box, type any string to describe this scope, and then choose the OK button.

Note When you finish creating a scope, a message prompts you that the scope has not been activated, and then allows you to choose Yes to activate the scope immediately. However, you should not activate a new scope until you have defined the DHCP options to be configured for this scope.

Now you can continue with the procedures described in "Configuring DHCP Option Types" and "Administering DHCP Clients" later in this chapter. After you have configured the options for this scope, you must activate it so that DHCP client computers on the related subnet can begin using DHCP for dynamic TCP/IP configuration.

To activate a DHCP scope

• From the Scope menu, choose the Activate command to make this scope active.

The menu command name changes to Deactivate when the selected scope is currently active.