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ICT-Hotlist Topic

How to: monitor Windows DNS servers for use of certain server names.

Of course one can use network sniffer software such as Wireshark or other tools1 to monitor the DNS traffic for certain server name requests. The standard default debug logging of the DNS service can give a quick indication without installing additional software.


  • On the DNS server turn on Debug Logging (select properties on the DNS-Service) and set the following properties:
  • Windows 2012 r2 DNS server properties dialog showing the required Debug Logging options.
    Windows 2012 r2 DNS server properties dialog showing the required Debug Logging options.
  • The default logfile can be found here: %systemroot%\System32\dns\Dns.log
  • The log contains entries in the format
    • Date (month,day,year)
    • Time
    • Don't care
    • Don't care
    • Don't care
    • UDP the protocol used
    • Rcv it is a request to the DNS server
    • Originating IP-address
    • Don't care
    • Q type is query
    • [] Don't care
    • Address type A => IPv4 AAAA => IPv6
    • The requested domain with length denotifiers (PASCAL style)
  • 5/31/2014 5:00:28 PM 1290 PACKET  0000000006F3D750 UDP Rcv      000a   Q [0001   D   NOERROR] A      (8)vansoest(2)it(0)
    5/31/2014 5:00:28 PM 1290 PACKET  00000000070EEED0 UDP Rcv      000b   Q [0001   D   NOERROR] AAAA   (8)vansoest(2)it(0)
    This example shows a DNS request from the system with ip-address (can be IPv4 or IPv6 address format) requesting the ip-address for
Just filter the log on the server name you need (for example "vansoest") and you have a list of systems still referencing the server.
No reboot or restart of the DNS server and service required.

Footnote 1

Kevin Manning of Comparitech was so kind to report a broken link about Microsoft's Message Analyzer that is discontinued. On this site you can find an overview of packet sniffers
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