Solve Windows 2000 DNS server problems

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Peter Parsons

Published: 19 May 2003 13:03 BST

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The BOOT file
When checking the BOOT file, you should see various entries such as the primary record, the secondary record (if applicable in your DNS installation), and a cache record.

You should see something like this:

• 1 primary tweedldee.com tweedldee.com.dns
• 2 secondary tweedldum.com 100.100.100.103 tweedldum.com.dns
• 3 cache . cache.dns

Please note that the numbers on the left are line numbers I put in for my example -- you won't see them in the BOOT file. Line 1 indicates that this DNS server is primary and authoritative for tweedldee.com and that the zone file for this domain is called tweedldee.com.dns. Line 2 indicates that this server is also a secondary server for tweedldum.com. The IP address you see is the one pointing to the primary name server of tweedldum.com. The tweedldum.com.dns entry is the name of the secondary zone file for tweedldum.com.

In Line 3, you'll see the entry for the cache file. The dot refers to the root servers, whether they're local or the 13 on the Internet. They have no name because they are the top-level name resolvers. Finally, cache.dns refers to the name of the file itself.

So, if your dead DNS server has intact cache and zone files, and it received boot information from Active Directory or the registry, how do you fix it and get DNS going again?

First, install DNS on a new server and set it to boot from the BOOT file instead of from Active Directory and/or the registry. Then stop the DNS service and restore the cache and zone files to %systemroot%\system32\dns.

But, you say, you don't have a BOOT file, so you can't start DNS anyway. Maybe not, but using the information and layout above, you can write your own BOOT file in no time. You know what needs to be in your BOOT file because you know the names of all the zone files. If you need IP addresses for secondary records, you can open the relevant secondary zone file(s) and find them. Once this is done, you can start the DNS server again, and you should have your network up and running in no time.

Apart from its simplicity, this method gets Active Directory working again because the zone files contain all the necessary data, such as SRV records, needed to locate domain controllers for Active Directory replication and other Active Directory activities. To be sure it all works, run NSLOOKUP and run some queries.

Best practices
Here are some suggestions to help you design and configure your DNS deployment to prevent trouble:

• Make sure you have redundancy in your DNS server infrastructure. This means using more than one server to host each DNS zone.
• Make sure that the email address for the zone administrator is correctly entered into the zone information because DNS will use this address to send alerts for a variety of DNS illnesses. Email addresses in DNS are entered with a period (.), not an ampersand (@). For example, admin@mydomain.com must be entered as admin.mydomain.com.
• Use ADI zones, but set the BootMethod to use the BOOT file rather than Active Directory or the registry.
• Use secure DDNS.
• If you have a large network, consider installing one or more dedicated caching-only DNS servers to offload the other servers.
• If you're using DHCP with the above option, make sure you provide each client with two DNS server addresses in case one of the DNS servers breaks. This way, clients can resolve names and they can also continue to update their A and PTR records via DDNS.

Of course, if none of these approaches fits, you'll most likely either need to restore DNS services from a backup, build a new domain from scratch (ouch), or find a new job, preferably on some distant beach.

Editorial disclaimer: The authors and editors have taken care in preparation of the content contained herein but make no expressed or implied warranty of any kind and assume no responsibility for errors or omissions. No liability is assumed for any damages. Always have a verified backup before making any changes.

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