Editing the DNS Root Hints Files

by Chris Sanders [Published on 6 Dec. 2007 / Last Updated on 6 Dec. 2007]

DNS Root Hints are essential for the location of records that takes place during DNS recursion. Here are a couple of quick tips regarding DNS Root Hints.

In order for DNS server recursion to work properly, the DNS server needs to know where to begin looking for names in the DNS namespace. This information is made available through root hints. These are resource records used by the DNS service to locate servers authoritative for the root of the DNS domain namespace tree.

Be default, Windows 2003 DNS servers use a preset root hints file stored at C:\Windows\System32\Dns\Cache.dns. This file contains a listing of all of the addresses of the root servers in the Internet DNS namespace. This means that if you are using the DNS server service to resolve Internet-based DNS names, the root hints file doesn’t need to be modified at all. However, if you are using DNS service on a private network you can edit or replace this file with similar records that point to your own internal DNS root servers.

It is important to note that DNS root servers should not use root hints at all, and by default Windows Server 2003 automatically deletes the Cache.dns file in these scenarios.


Chris Sanders is a network consultant for KeeFORCE, one of the most popular network consulting firms in western Kentucky. Chris is the author of the book Practical Packet Analysis as well as several technical articles. His personal website at www.chrissanders.org contains a great deal of information, articles, and guides related to network administration, network security, packet analysis, and general information technology.

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