An application, such as Microsoft Internet Explorer, cannot resolve domain names from some Domain Name System (DNS) servers. Because of this, you may not be able to access some Web sites. For example, you may receive the following error message in Internet Explorer when you try to access a Web site:
The page cannot be displayed The page you are looking for is currently unavailable. The Web site might be experiencing technical difficulties, or you may need to adjust your browser settings... Cannot find server or DNS Error
This problem may occur if the DNS server is queried for a non-"A" record, and the server replies with an authoritative response that returns NXDOMAIN or NAME_ERROR (Response Code, or RCODE, 3) even though an "A" (or Internet Protocol version 4, or IPv4, host) record for the queried name exists on that DNS server. NXDOMAIN or NAME_ERROR in the response indicates that there are "no records of any type for that name." Microsoft has found that some DNS server software does not support "AAAA" (Internet Protocol version 6 or IPv6) records and incorrectly responds with NXDOMAIN even though an "A" record exists for the site.
For example, this problem may occur when a Windows client computer that is running IPv6 tries to access a Web site. The Windows client will try to resolve the host name (for example, www.example.com) on behalf of applications that support both IPv6 and IPv4. To do this, the Windows client will query for both "AAAA" records and "A" records, unless the application specifies which protocol to use. If the DNS server replies with an authoritative response that returns NXDOMAIN or NAME_ERROR, Windows will return this response to applications, such as Internet Explorer. Because of this, the application will fail to resolve the host name and will be unable to access the site. Note that Windows clients will also cache this negative response. This prevents additional queries for this name from succeeding until the client cache is cleared.
Important In this example, if the DNS server that is used by the Windows IPv6 client caches negative responses, name resolution will also fail for other client computers when they use this same caching DNS server. This issue occurs regardless of the subsequent query type and regardless of whether the other client computers are running IPv6 or IPv4 only.
To resolve this problem, contact the administrator of the site that you are having problems with.
The DNS administrator of the site should contact the manufacturer of their DNS product for help resolving this issue. This may require an upgrade to the DNS server product or a change in the configuration of the DNS server or servers.
According to section 6.2.4 of RFC 1034 (see "References"), if there are "A" records that are hosted on the DNS server, the DNS server should not return a NXDOMAIN or NAME_ERROR response when the you query for "AAAA" records (or any non-"A" record). Instead, the DNS server should return NODATA or no error (RCODE 0) and an empty answer section if it does not recognize an "AAAA" name query.
For additional information about the IPv6 protocol for Microsoft Windows XP and Windows Server 2003, visit the following Microsoft Web site:
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