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Hack 38 Troubleshoot DNS
Here are some tips, tools, and resources to
help you troubleshoot DNS problems on Windows 2000/2003-based
networks.
DNS troubleshooting is usually straightforward,
because most errors tend to be simple configuration or setup errors.
To troubleshoot DNS, you must have details of the configuration of
any DNS resolvers and/or DNS servers and be able to use common DNS
troubleshooting tools. This hack provides some details and links to
tools you can use to troubleshoot DNS, as well as tips on how to
overcome common DNS errors.
DNS Troubleshooting Tools
Here are a few useful web sites that
offer tools for troubleshooting DNS:
www.DNSreport.com (http://www.dnsreport.com)
This site will check the DNS settings for an Internet zone and
provide prescriptive guidance on optimizing the settings.
www.DNSstuff.com (http://www.dnsstuff.com)
This site has a number of DNS tools that you can use to diagnose DNS
issues.
SamSpade.org (http://www.samspade.org)
This site has some good tools for DNS troubleshooting. It promotes
its tools and expertise as anti-spam utilities, as opposed to just
DNS troubleshooting. The site's tools page
(http://www.samspade.org/t/)
provides tools similar to those at www.DNSstuff.com. I have the Sam
Spade For Windows tool (http://www.samspade.org/ssw/) on my desktop
and use it a great deal.
AnalogX DNSDig (http://www.analogx.com/contents/dnsdig)
This page provides an online version of DIGa useful tool from
the Unix world that is used to troubleshoot DNS issues. (Why
can't Microsoft provide a port of DIG in Windows or
the resource kit?)
Squish.net DNS Checker (http://www.squish.net/dnscheck)
Given a record name and a record type, this page will return a report
that details all possible answers.
DNS Dump (http://www.reskit.net/DNS/dnsdump.cm_)
This is a truly awesome script by Dean Wells that exports/imports DNS
server configurations. Read carefully before using it, and make sure
you change the extension before you run it!
Troubleshooting Common DNS Issues
Here is a list of common problems and solutions that have been
discussed in online newsgroups:
Running nslookup returns nonexistent domain
If you run nslookup, you might see an error that
looks like this:
C:\>nslookup
*** Can't find server name for address 192.168.1.1: Non-existent domain
*** Default servers are not available
Default Server: UnKnown
Address: 192.168.1.1
When nslookup starts, it attempts do a reverse
lookup of the IP address of the DNS server. If the reverse lookup
fails, nslookup returns the preceding error
message, which is somewhat misleading. The solution is to either
install a reverse lookup zone for your workstations or to ignore the
message.
Netlogon Error 5774 - DNS Operation Refused
This error is typically caused by the use of a DNS server that does
not allow dynamic update or is set to refuse operations from your
computer. Sometimes, this is due to a workstation that points to the
ISP's DNS server instead of an internal DNS server.
In general, all internal servers and workstations should point to one
or more internal DNS servers that in turn point to a DNS server that
forwards to the Internet.
DNS Error 414 - The specified domain either does not exist or could not be contacted
This error usually occurs when the computer is configured without a
DNS domain name. If the computer is a DNS server that has only a
single label name (e.g., kona2 versus
kona2.reskit.net), any zone created will have
the default SOA and NS records created using just a single label.
This in turn will lead to invalid or failed referrals for the zone
used to provide lookups for this zone.
DNS Error 5504 - The DNS Server encountered an invalid domain name in a packet from X.X.X.X
This error indicates that the DNS server has received a packet with
an invalid domain name and the packet has been rejected. The most
common cause of this is DNS cache pollution, as described in
Knowledge Base (KB) article 241352 (http://support.microsoft.com/default.aspx?scid=kb;en-us;241352).
Troubleshooting dynamic update problems
Dynamic update is a DNS feature that enables hosts to update their
DNS details at the DNS server. Although easy to set up, there are
some ways in which DNS dynamic update can fail. See the KB article
287156 for more details (http://support.microsoft.com/default.aspx?scid=kb;en-us;287156)
Windows Server 2003 cannot resolve addresses that Windows 2000 can
In some cases, it appears that server is just not functioning and not
resolving some names. The cause is that Extension Mechanisms for DNS
(EDNS0) requests from the 2003 DNS server are not recognized by all
other DNS servers. To resolve this, you should disable EDNS0
requests, using the DNScmd program from the
Windows Server 2003 Support Tools folder and type dnscmd
/config /enableednsprobes at a command prompt.
DNS Newsgroups
If the previous tips and tools do not help and you are using any version of
Microsoft Windows (or DOS, for that matter), consider posting a query
to the microsoft.public.win2000.dns newsgroup.
This newsgroup can be obtained from
DNS Books
Finally, here are two books you can use to learn more about
troubleshooting DNS issues:
DNS and BIND
By Cricket Liu and Paul Ablitz (O'Reilly). This book
is possibly the best introduction to DNS in existence.
It's Unix-based, but it's still a
good book.
Windows 2000 DNS
By Herman Knief, Roger Abell, Jeffery Graham, and Andrew Daniels
(O'Reilly). This is a pretty good Windows 2000 DNS
book.
Thomas Lee
