Installing and Configuring a DHCP Server on part 3
Creating an Address Scope
After you have authorized a server on the network, you can create a scope of addresses that the DHCP server can administer to clients. From the MMC utility, click once on the server you want to administer, and then select New Scope from the Action menu. The New Scope Wizard pops up. Alternatively, you can right-click the server and select New Scope. Click Next to dismiss the introductory dialog box and continue creating an address scope. The wizard then prompts you through the following steps:
- A dialog box pops up that you can use to give the scope a name and description. The description is optional, but you must at least supply a name for the scope so that it can be differentiated from other scopes you might create. Enter the name and, if you want, a description and click Next.
- The next dialog box prompts you to enter the range of IP addresses for this scope. Enter a starting address and an ending address. You also should enter a subnet mask associated with this address range. The subnet mask can be entered in the traditional way using dotted-decimal notation, or you can specify the mask by indicating the number of bits in the Length field (as in CIDR notation). When finished, click Next.
- The next dialog box enables you to specify any addresses that fall within the range you have entered that you want to exclude from the scope. You can enter a single address and click the Add button, or you can enter a range of addresses (starting and ending addresses) and click the Add button. If you change your mind about an address, highlight it and click the Remove button. When finished adding addresses to be excluded, click Next. You should exclude the DHCP server’s own address if it falls within the range of addresses you defined in the preceding step.
- Next, you are prompted to enter the amount of time to lease the addresses in this scope. This dialog box defaults to 8 days. As it suggests, you should consider creating scopes that have lease values relevant to your network. For example, mobile computers that frequently move from one place to another can be given a shorter lease time, thus keeping your address pool from becoming populated by unexpired, unused leases. This dialog box also enables you to specify the lease in hours, minutes, and seconds.
- The DHCP packet can contain various options. The dialog box asks if you want to enter options valid for this scope or to put it off until another time. For this example, go ahead and configure the options. Leave the Yes, I Want to Configure These Options Now radio button selected, and click Next.
- 6. The first option prompts you to enter the default gateway for the subnet covered by this range of addresses. Enter one or more IP addresses for the routers you want to use, clicking the Add button to add each one. Note that here you are entering the default gateway to which clients will send IP datagrams when the destination is not on the local subnet. This is not the gateway computer that serves as a BOOTP or DHCP Relay Agent. Again, if you change your mind, you can highlight any router address and click the Remove button to delete it from this list. Click Next when you have finished adding routers.
- Next, a dialog box prompts you to enter the parent name of your network. This is the name of the domain that client computers are configured to use for DNS name resolution. You can see that you can also enter the names or addresses of domain name servers the client is configured to use. If you enter a server name, click Resolve to have the wizard look up the address, or enter an address and click Add to add it to the list. Use the Remove button if you change your mind. Place the order of DNS servers in the same order in which you want clients to access them. You can highlight a server in the list and use the Up and Down buttons to change the order.
- If you are still using Microsoft’s Windows Internet Naming Service (WINS), you can use the next dialog box to enter the names or addresses of the WINS servers. If you enter the name, use the Resolve button again to have the server translate the WINS server’s name to an IP address.
- Finally, a dialog box asks whether you want to activate the scope now or later. The server does not begin allocating addresses in the scope to clients until the scope is activated. After making your choice, click Next.
- A final dialog box notifies you that the wizard is finished creating the scope. Click the Finish button.
If you did not choose to activate the scope, you can do so later by right-clicking on the scope and selecting Activate. Alternatively, click once on the scope and select Activate from the Action menu.
The Status field in this display tells you whether the scope is active, and the Description field can be useful when you create multiple scopes and need a reminder of their use. After the scope has been activated, clients that boot on the network and that have been configured to use a DHCP server can now receive configuration information from this DHCP server. If you expand the scope by clicking on the plus sign in the left pane, you can see that there are four other objects that can be managed.
You can click on any of the other objects to see information. For example, if you want to see what options are enabled in this scope, click Scope Options. The option number (from the RFCs), name, and values for the options are displayed. In the case of this initial setup using the wizard, you would see options for the default router (gateway), DNS server, and domain name. If you entered an address for a WINS server, that option would also be displayed.
Reserving a Client Address
You can choose to exclude certain addresses from a scope that you know are configured manually, such as routers. However, you might want to use the Reservation method to reserve an address for a DHCP client that might need to keep the same IP address, but obtain other information from the DHCP server at times. A DNS server is a good example of a server that should have a reserved address.
To reserve an address within a scope, expand the scope in the MMC console and open up the Reservation dialog box either by highlighting the Reservation object and selecting New Reservation from the Action menu, or by right-clicking the Reservations object and making the same selection.
More Help'n Tips: action menu, activate, activate the scope, address, address and click, addresses, box, button, click, click next, click the remove, client, clients, configured, creating, creating an address, description, dhcp, dhcp server, dialog, dialog box, dialog box asks, dialog box prompts, dns, enter, enter the name, enter the names, example, expand the scope, gateway, ip, lease, name, names or addresses, network, next, next dialog, next dialog box, options, prompts, range, range of addresses, remove button, reservation, reserve an address, scope, select new scope, server, subnet, wins, within the range, wizard.
- May 18th
Leave a Reply