Single-Domain Migration

Staying with Windows NT might have made sense to the administrators of small shops and single domains: Although NT Server isn't as sexy as Windows 2000 Server, when correctly installed and configured, NT Server is stable and reliable. Also, requirements to meet and concepts to learn clutter the Win2K migration path. However, DNS and Active Directory (AD) offer great benefits, and Microsoft has made the upgrade process as simple as possible. Now is the time for single-domain administrators to migrate their NT infrastructure completely to Win2K—DNS, AD, and all.

Putting Pencil to Paper
After you brush up on the concepts behind AD and DNS, you'll be ready to make a few decisions about your migration. For information about AD and DNS, see Mark Minasi, "DNS and Active Directory," page 39 and "Related Articles in Previous Issues," page 46. Because planning results in a smoother migration, I don't recommend making migration decisions on the fly.

First, you need to choose a name for your top-level Win2K domain. Rather than choose company.com and confuse your company's private and public domain names, choose a name of the form company.internal. DNS servers use both the machine name and the domain name to reference a machine in an AD network. Because your domain name will be a part of every host name in your network, I recommend keeping the name short and applicable. You probably don't want chicago.il.company.internal to be the domain name attached to every host name in your network—especially if your organization opens an office in a city other than Chicago.

You also need to plan around any existing DNS infrastructure your NT network might have. Most NT networks that have DNS infrastructures use DNS for only client-side Internet communications. Your NT network's client workstations are likely configured one of two ways for Internet DNS resolution: Workstations send requests to either your ISP's DNS servers or a DNS host server in your NT network.

Workstations configured to use your ISP's DNS servers send all DNS name resolution requests to those servers. This configuration is acceptable for NT networks, whose only DNS resolution requests are for external DNS names. But after you migrate to AD and adopt internal DNS host names, you don't want your Win2K network's workstations sending their internal DNS name resolution requests to your ISP's DNS servers. Those servers most likely would not know a system named www.company.internal.

Workstations in an NT network with an internal DNS host server send all DNS requests to that server. If you want to use this DNS server in your AD network, the server needs to support service resource records (SRV RRs). NT's DNS service won't cut it.

Both of the above DNS infrastructures require you to install Win2K's DNS service when you upgrade. You have two options for installing DNS on your network: building a standalone DNS server before migration or letting the DC promotion program, Dcpromo, install DNS on the first domain controller (DC) you migrate to Win2K. Using Dcpromo is the path of least resistance and the approach I recommend.

Upgrading your PDC
Of course, you'll back up your PDC, DCs, and member servers before you begin the migration. You'll also need to verify that each system you intend to upgrade meets (or preferably, exceeds) Win2K Server's minimum hardware specifications. Migrate your NT domain's PDC first.

To begin the upgrade, insert the Win2K Server CD-ROM into your PDC, then choose the Upgrade option or run winnt32.exe from the CD-ROM's \i386 directory. Both approaches launch a Win2K Server upgrade and leave the server's settings in place. Win2K Server installation takes time, so get a cup of coffee and check your voicemail while you wait. The installation process eventually logs on as Administrator and starts Dcpromo.

Dcpromo is one of Win2K's most significant advantages over NT. Not only can you use Dcpromo for your Win2K upgrade, you can also use it to remove the DC function from or add it to a server without reinstalling Win2K Server from scratch. The program's straightforward Active Directory Installation Wizard asks several questions, but the two most crucial are Do you want to create a new domain tree or a new child domain in an existing domain tree? and Do you want to create a new forest or join an existing forest?