Note that a DHCP server still doesn’t do anything until you configure a scope, the set of configuration settings that will be handed out to a group of clients. Like many things in Windows 2000, the scope creation process is handled via a wizard. In order to create a scope, right-click on the DHCP server and choose New Scope. The wizard will walk you through the entire process, including the configuration of a valid range of IP addresses, subnet mask, and options such as a default gateway (Router), DNS Servers to be used, and so forth. After the scope is configured, it still needs to be activated (right-click and choose Activate). The properties of the scope will be displayed categorized according to address pool, active leases, reservations, and scope options included.
Note that after the server is authorized and a scope is configured, the arrow on the server icon above has changed to green and now points upwards. A few additional notes about scopes under Windows 2000:
- scopes can be aggregated or combined in order to create Superscopes. This would allow you to hand out IP addresses in non-contiguous ranges to hosts on a given subnet if necessary.
- If you want to change the subnet mask value associated with a scope, you’ll need to delete and recreate the scope.
- The default lease time for addresses in a scope is 8 days. This is different that the NT 4 default of 72 hours, but can be changed to meet the needs of your environment.
- Ranges of IP addresses should be present only in a single scope. Since DHCP servers do not coordinate with one another, if two servers both have the same range of addresses in their scopes, duplicate IP addresses could be handed out on the network. Also be sure to exclude any statically-assigned IP addresses from scopes.
- In order to create fault-tolerant scopes, configure 2 (or more) DHCP servers, and split the range of addresses in each scope between them. In this configuration if one server fails, the other will still be capable of handing out valid IP addresses to clients.
- Options can be handed out at 4 different levels: Server (which impact all scopes), Scope (which impact only that scope), Client (set on a client reservation), and Class (for computers that fall into a defined class grouping). More on this later in the series, just be aware of the levels at which options can be assigned for now.