Microsoft

Talking Shop: Know Dynamic DNS before trying Windows 2000 exams

Dynamic DNS is an integral part of the Windows 2000 certification exams


Microsoft warns that its Windows 2000 Server MCP exam tests candidates on their ability to configure and troubleshoot Windows 2000 network connections. As part of your preparation, you should ensure that you’re familiar with the workings of Win2K’s Dynamic Domain Name System (DDNS). It’s a safe bet you’ll see DDNS questions pop up on other exams, too, including:
  • Exam 70-216—Implementing and Administering a Microsoft Windows 2000 Network Infrastructure
  • Exam 70-217—Implementing and Administering a Microsoft Windows 2000 Directory Services Infrastructure

New in Windows 2000
Windows NT 4.0 requires that a server’s static DNS database be maintained manually to track which hosts have which IP addresses. Even if you’re diligent about updating DNS entries for your network, the odds are you haven’t made it a priority to remove stagnant entries that are no longer used. As a result, the DNS database can quickly become unwieldy. Windows 2000 has helped remedy this issue by implementing Dynamic DNS.

Win2K incorporates RFC2136 standards to power Dynamic DNS updates. DDNS plays a significant role in helping Active Directory and DNS automate name resolution with the assistance of DHCP.

DDNS enables Windows 2000 systems to update their forward lookup DNS records. In addition, DDNS enables servers running DHCP and WINS to update the forward and reverse lookup entries the servers store for each client. Servers running WINS can now enter NetBIOS names automatically into any dynamically updated database.

Active Directory also benefits from DDNS. As a result of the dynamic update capability, servers running Active Directory Services can automatically list themselves in a DNS database.

Make no mistake: DNS has replaced WINS as the preferred method of name resolution in Windows 2000. In fact, networks that eventually eliminate legacy Windows 9x and Windows NT systems will no longer require WINS servers.

How's it work?
Configuring DDNS is simple in Windows 2000. Follow these steps:
  1. Click Start | Programs | Administrative Tools and select DNS.
  2. Right-click on the zone you want to configure to use dynamic updates and select Properties.
  3. In the General tab, choose Yes from the Allow Dynamic Updates drop-down list, as shown in Figure A.
  4. Click OK to close the Properties screen.

Figure A
Use the DNS MMC console to configure DDNS in Windows 2000.


You’ll also want to configure your DHCP server to automatically update DNS changes. Configure the DHCP service to make dynamic changes by following these steps:
  1. Click Start | Programs | Administrative Tools and select DHCP.
  2. Right-click on the DHCP scope you want to configure and click Properties.
  3. Click the DNS tab, shown in Figure B.
  4. Configure the respective DHCP settings to dynamically update with DNS.
  5. Click OK to close the open dialog boxes.

Figure B
DHCP must be configured appropriately to update DNS automatically with addressing changes.


You can also set options to help limit the size of the DNS database. Follow these steps:
  1. Click Start | Programs | Administrative Tools and select DNS.
  2. Right-click on the zone you want to configure and select Properties.
  3. In the General tab, click the Aging button to open the Zone Aging/Scavenging Properties dialog box, shown in Figure C.
  4. Select the Scavenge Stale Resource Records check box to enable deletion of records that have not been refreshed in a long time. Using the provided boxes, specify the interval at which stale records should be discarded.
  5. Click OK twice to close the Properties screens.

Figure C
Scavenging enables the deletion of stale records, helping to keep the DNS database manageable.


WINS tip
If your network still possesses some static DNS servers, be sure to configure WINS lookup for DHCP systems that rely upon NetBIOS. Otherwise, systems are likely to experience failed DNS lookups.
Configure WINS forward lookup by right-clicking on the DNS zone you want to enable WINS forwarding for. Select Properties and click the WINS tab in the resulting dialog box. Then, select the Use WINS Forward Lookup check box.


Eckel's take
Entire doctorates are written on minute aspects of protocols such as DDNS. I’ve taken only a brief look at the features and benefits of DDNS. Hopefully, your interest has been piqued sufficiently to prompt you to spend more time working with and understanding the configuration of DDNS and DHCP.

Configuring DDNS in Windows 2000 can greatly simplify DNS, WINS, and DHCP administration. Experimenting with DDNS features will help you gain valuable knowledge, much of which will come in handy when you take Windows 2000 exams. This article showed you how DDNS features work, as well as how you can get started configuring automated updates for critical databases.

Do you have tips for working with DDNS?
We look forward to getting your input and hearing about your experiences regarding this important topic. Join the discussion below or send the editor an e-mail.

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