Tech Tip: Run apps in compatibility mode/Create a reverse lookup zone in Win2K

Learn how to run apps in compatibility mode and create a reverse lookup zone.

Windows 2000 Professional: Configure application compatibility settings

Windows 2000 with Service Pack 2 or later includes a tool that you can use to configure compatibility mode settings for applications. This can enable an older application to run on Windows 2000 when it might otherwise experience problems.

By default, Windows doesn't display compatibility settings. To expose these settings, open a command prompt, and enter the following command. (If you didn't install Windows in \winnt, replace \winnt with the proper location.)

Regsvr32 \winnt\apppatch\slayerui.dll

After registering the DLL, create a shortcut to the application for which you want to configure compatibility settings. Right-click the shortcut, and select Properties. On the Compatibility tab, select the Run In Compatibility Mode check box, and choose a compatibility layer from the drop-down list. When you launch the application from the shortcut, Windows uses settings specific to the selected compatibility mode to run the application.

If you need more control over application compatibility, try the Application Compatibility utility (Apcompat.exe), which you'll find in the Support folder on the Windows 2000 CD. This tool offers options and features you can use to fine-tune application compatibility.

Windows 2000 Server: Create a DNS reverse lookup zone

DNS allows two main types of queries: forward lookups and reverse lookups. A forward lookup searches for an IP address based on a provided host name. For example, when you browse to, your operating system's DNS resolver queries DNS for a www host record in the domain.

A reverse lookup performs the opposite. It queries DNS for a host name based on an IP address. For example, some e-mail servers perform a reverse DNS lookup on a sending mail server to determine that the host name offered by the remote mail server actually matches the IP address of the SMTP connection attempting to deliver the message.

Windows 2000's DNS service supports both forward and reverse lookup zones. If you want your DNS server to support reverse lookups, you need to create a reverse lookup zone for each subnet you want to support.

To create a reverse lookup zone, follow these steps:

  1. Open the DNS console, and expand the server where you want to create the zone.
  2. Right-click Reverse Lookup Zones, and choose New Zone to launch the New Zone Wizard.
  3. Click Next, choose Standard Primary, and click Next.
  4. In the Network ID field, enter the first three octets of the zone's IP address, and click Next.
  5. When the wizard offers a name for the DNS zone file, click Next to accept the default name, and click Finish.

After creating the zone, you need to add pointer resource (PTR) records to the zone. These records associate an IP address with a host name. You can create the PTR records explicitly in the reverse zone, or the DNS console can create the PTR records automatically when you create records in the forward lookup zone.

Just because you host your own DNS services doesn't mean that reverse DNS makes it to your DNS servers. Your Internet service provider (ISP) might handle reverse lookup for your subnet. If you're not sure, check with your ISP.