Installing DHCP Service on your Windows NT server

DHCP (Dynamic Host Configuration Protocol) offers a painless way to manage TCP/IP addresses on your network. Fortunately, setting up this protocol on your Windows NT server is also an easy process. In this article, we'll show you how to configure server-side DHCP support.

Implementing DHCP on your Windows NT server

First, you'll design the basic layout of your DHCP system, as we discussed in the preceding article. Then, you'll be ready to install DHCP on your server. The protocol ships as one of Win-dows NT's services, so you don't need to buy any additional software.

To install DHCP support on your server, right-click on Network Neighborhood and select Properties. When the Network window appears, open the Services tab and click the Add button. Find and select Microsoft DHCP Server in the list of available services and click OK. (The install process may ask for your Windows NT CD.) Microsoft DHCP Server will now appear in the list of avail-able services, as shown in Figure A. Click OK to dismiss the Select Network Service dialog box and then restart Windows NT to load DHCP.

Figure A 

You can install DHCP as a service in Windows NT.

Configuring DHCP

When your server reboots, you must configure it before the server can start passing out TCP/IP addresses with your new protocol. To begin, open the Programs menu's Administrative Tools (Common) submenu and select DHCP Manager to open the screen shown in Figure B.

Figure B You configure DHCP using the DHCP Manager.

Your first step is to create a DHCP Server on your NT server. Select Add... from the DHCP Manager's Server menu to open the Add DHCP Server to Server List dialog box. Enter the TCP/IP address of your server in the DHCP Server text box and click OK. The server will now appear in the DHCP Server's window.

Next, you must create a scope for your server. Scope is Microsoft's terminology for a range of TCP/IP addresses. To begin, select Create from the Scope menu to open the Create Scope dialog box, shown in Figure C. Here, you'll provide all the information for the range of addresses you want to use for your workstations. Enter the TCP/IP address that begins the range in the Start Address text box and enter the closing TCP/IP address in the End Address text box. In the Subnet Mask field, enter the subnet mask for your network. (The subnet mask controls the total number of available addresses for the range of addresses you specify.)

Figure C These controls create a scope, or a range of TCP/IP addresses.

If you want to exclude a particular address within the scope you're creating, enter the address in both the Start Address and End Address text boxes under the Exclusion Range section. If you want to exclude an entire range, enter the range's starting and ending addresses in the Exclusion Range Start Address and End Address text boxes. Click Add to place your excluded address or range in the Excluded Addresses list box. Your DHCP server won't use any addresses in this list.

Next, you must specify the length of the DHCP lease your server will issue to clients. If you want to make the lease length unlimited, select the Unlimited radio button. In all other cases, click the Limited To radio button and select the length of the lease expressed in days, hours, and minutes.

NT's default DHCP lease length is three days. Your decision to make the lease longer or shorter should be determined by your network configuration. Shorter leases increase network traffic because your clients will ask for new addresses more often. This approach may be desirable if you have a limited number of addresses and many clients who need them. In this scenario, inactive clients don't tie up valuable addresses. You may also want leases to be available faster if you have many clients, such as notebooks, that travel frequently from subnetwork to subnetwork.

Longer leases reduce network traffic due to a lower number of renewal requests. If you have plenty of addresses to go around, you can let your clients keep their leases for an extended period. This approach also increases the overall stability of your network and makes details easier to track.

You can create a name for the DHCP scope and add comment information by filling out the appropriate fields. After you've made all your changes, click OK to close the Create Scope dialog box.

A little more info

Windows NT lets you customize options for your DHCP scope and clients by simply adding information about things such as DNS servers, Time servers, and Routers. To do this, select Scope from the DHCP Manager's DHCP Options menu. When you do, your workstation will display the screen shown in Figure D. To add a service, select it from the Unused Options list and click Add. Then, click the Value button to set an address or value for the option.

Figure D You can add customized information for your DHCP server and clients.

You can also use the DHCP Manager to permanently assign addresses to workstations on your network. To do so, select Add Reservations from the Scope menu to open the Add Reserved Client window. Enter the TCP/IP address you want to reserve in the IP Address text box. Next, enter the Media Access Control (MAC) address of your workstation's network card in the Unique Identifier text box. You can also opt to enter a computer name and comment in the Client Name and Comment text boxes. Click Add when you've finished making your changes.

Once you've created your DHCP scope, just restart your Windows NT server and it will be ready for use with DHCP. The final phase of your project is setting up the DHCP protocol on your workstations.

Managing passwords

Managing passwords can be a tedious task. Password Keeper for Windows 95/NT, a freeware utility, can make this chore easier by storing your frequently used passwords.
You can store, edit, and print password information from each password file, which can contain up to 500 account entries. Password Keeper stores data files in an encrypted format to prevent unauthorized users from accessing and viewing them. You can also copy passwords to the Clipboard and paste them into other login programs. You can download Password Keeper at www.execpc.com/~sbd/PASSKEEP.ZIP.

Viewing configured workstations

After you've configured your servers and workstations to use DHCP, you can use DHCP Manager on your servers to see TCP/IP information about client leases. To access this information, select Active Leases from the Scope menu. You'll then see the Active Leases screen shown in Figure A.

Figure A 

You can use this tool to view which clients have what addresses. The DHCP clients on your network appear in the Client list box. You can sort the list by IP address or name by clicking the appropriate radio button. If you want to view detailed information about a client's configuration, highlight the client's name and click Properties.