I've got a little domain to manage some hosts in a test environment. I've noticed a strange problem involving the random disappearence of a DNS record from the DNS server set up on the DC.

I've got two identical domain clients, client01 and client02. Both have their IP addresses assigned by a DHCP server I don't control. Both have their DNS settings manually overridden to have the DC as their only DNS server, with the correct domain name put in the DNS suffix box and the 'register this connection's addresses in DNS' boxes are both checked. Both clients are Windows 7.

Client 1 has a DNS entry that's maintained in the DNS server, so the DC can ping client1 by name. Client 2 occasionally gets an entry for a short period of time, usually after a reboot or the issue of a ipconfig /registerdns command. However, this then disappears after about 30 minutes.

Any idea what's causing this?

  • What is the lease time on DHCP? Do you have DHCP set to automaticly update the DNS record? – Nixphoe May 13 '11 at 15:42
  • The DHCP lease time is fairly lengthy - a couple of days from memory. Thing is, the DHCP server isn't controlled or managed by me at all, so has no interaction with my DNS server. – growse May 13 '11 at 19:34

Is scavenging enabled on your zone? If so, dependent upon your lease/ scavenging settings, the records that become stale would be automatically removed.

  • I'll go double-check, but that makes sense. Question is why it would think a DNS record has become stale for one client, but not the other? – growse May 13 '11 at 19:35
  • Probably one of them isn't updating itself properly. But I've seen some oddities - I have a server whose AAAA record disappears a lot, though the A records is solid. – Richard Gadsden May 14 '11 at 15:05

Grabbed this info from: http://technet.microsoft.com/en-us/library/cc961419.aspx

DNS Log You can configure the DNS server to create a log file that records the following types of events:


Notification messages from other servers

Dynamic updates

Content of the question section for DNS query message

Content of the answer section for DNS query messages

Number of queries this server sends

Number of queries this server has received

Number of DNS requests received over a UDP port

Number of DNS requests received over a TCP port

Number of full packets sent by the server

Number of packets written through by the server and back to the zone

The DNS log appears in % SystemRoot %\System32\dns\Dns.log. Because the log is in RTF format, you must use WordPad to view it.

You can change the directory and file name in which the DNS log appears by adding the following entry to the registry with the REG_SZ data type:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\DNS \Parameters\ LogFilePath

Set the value of LogFilePath equal to the file path and file name where you want to locate the DNS log.

By default, the maximum file size of Dns.log is 4 MB. If you want to change the size, add the following entry to the registry with the REG_DWORD data type:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\DNS \Parameters\ LogFileMaxSize

Set the value of LogFileMaxSize equal to the desired file size in bytes. The minimum size is 64 Kb.

Once the log file reaches the maximum size, Windows 2000 writes over the beginning of the file. If you make the value higher, data persists for a longer time, but the log file consumes more disk space. If you make the value smaller, the log file uses less disk space, but the data persists for a shorter time.


Do not leave DNS logging during normal operation because it consumes both processing and hard disk resources. Enable it only when diagnosing and solving DNS problems.

To configure the server to log DNS events

1.In the DNS console, click the box next to the server, right-click the server, and then click Properties.

2.Click the Logging tab, and then select the options you want to log.

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Stopping and Flushing the Cache In addition to flushing the cache by using Ipconfig, you can stop and flush the cache by stopping and starting the client.

To stop the client

At the command prompt, type the following: net stop " dns client "

To start the client

At the command prompt, type the following: net start " dns client "

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