Sams Teach Yourself MCSE Windows NT Server 4 in 14 Days
(Publisher: Macmillan Computer Publishing)
Author(s): David Schaer, et al
ISBN: 0672311283
Publication Date: 12/15/97

The second-level domain is defined by the organization that registers under a top-level domain. Further second-level domains can also be defined under this second-level domain. For example, Hewlett-Packard owns the second-level domain hp. This domain falls under the com top-level domain. This gives Hewlett-Packard the domain name hp.com. Hewlett-Packard also maintains a Web site on a server called www. This server falls under the second-level domain hp. Thus, the domain name for that server is http://www.hp.com.

As you can see, the hierarchical nature of DNS provides much more flexibility than a simple flat name space. With a flat name space, only one host name in the database could ever be called www.

11.5.1. Configuring the Microsoft DNS Server

The following sections take you through the setup and configuration of the Microsoft DNS Server. They cover the installation of DNS, the configuration and optimization of zones and host records, and the methods of name resolution that DNS uses.

Installing the DNS Server Service

To install the DNS Server service on a Windows NT server, do the following:

1.  Open the Control Panel/Network and select the Services property sheet.

2.  Choose the Add button.

3.  On the list presented, select Microsoft DNS Server and choose OK.

4.  You are asked for the path of the Windows NT Server 4.0 installation CD-ROM. Enter the drive letter for your CD-ROM or choose Browse to select an appropriate location. The installation will then take place.

5.  Choose Close on the Network Control Panel.

After this is finished, the DNS service should be running and will run automatically whenever the computer is started. After installing the DNS server, it automatically performs as a caching-only name server for the Internet.

Zone of Authority

A zone of authority is simply a portion of the domain name space for which a name server is responsible. The name server maintains a database of host names and IP addresses for the computers that fall into its authority and is responsible for resolving queries of those names. An authority can really be thought of as all of the host names and IP address mappings that a particular name server is responsible for keeping up with and being the ultimate authority on.

A zone is defined as the part of the name space that is documented in the zone file. A name server can contain more than one zone. A zone of authority must contain at least one domain, known as the root domain. From the preceding example, a zone might be defined for Hewlett-Packard. The root domain would be hp.

Name Server Roles in DNS

A DNS server can play four roles:

•  Primary Name Server: The primary name server hosts the local zone files, and all changes made to the file are made on this server.

•  Secondary Name Server: The secondary name server is a backup to another name server. It downloads the database information from a master name server. The secondary name server provides redundancy of data and helps reduce the query load on the primary name server.

•  Master Name Server: A name server from which a secondary name server downloads its database information. The master name server can be either a primary or a secondary name server.

•  Caching-Only Name Server: All name servers cache the queries that they have resolved locally in addition to their other services. The caching-only name server, however, only performs and caches queries. It is not an authority over any zone data.

Setting Up Zones, Domains, and Resource Records

Before your DNS server can act as anything other than a caching-only server, you must provide it with information about your network. This includes adding zones of authority, domains, and resource records. The tool you use to administer your DNS server is called Domain Name Service Manager, and it is available in the Administrative Tools group under the Start menu. Domain Name Service Manager is pictured in Figure 11.26.

Figure 11.26.  Domain Name Service Manager.

To create a new zone, highlight the server for which you want to configure the zone and select New Zone under the DNS menu. This brings up the dialog box shown in Figure 11.27.

Figure 11.27.  Creating a new zone with DNS Manager.

You might need to add a server before creating a zone. If you do, choose New Server under the DNS menu and enter the name or IP address of the server.

Select whether you want to create a primary or secondary zone. If you are creating a secondary zone, you must also fill in the master zone and master server name. After you have done this, click Next and you see the dialog box shown in Figure 11.28.

Figure 11.28.  Filling in new zone information.

The zone name is the name by which your zone is referenced and is usually something like servername.com. The zone file can be anything, but must end with the extension .dns. After you have entered the zone name, press Tab to have Windows NT name the file for you. After you have finished creating your zone, the DNS Manager window should look like Figure 11.29.

Figure 11.29.  A new zone in DNS Manager.