DHCP 2008R2- Reservation are disappearing


  • We have 2 DHCP servers 2008 R2. The both servers are DCs. We use a lot of reservations for Printers and APs (Access Point).
    However we can find a few reservations disappearing every day. But not absolutely. We cannot see them in DHCP MMC GUI and they are not in netsh dhcp server Dump either.
     but they can be seen in "netsh dhcp server scope ..... sh reservedip".
    The problem is, those reservations are not leased and the network devices are not able to boot.
    When we do Reconcile - Verify , we can see some IP address in different scopes
    All scopes  are consistent after Reconcile. But within a few days the problem occurs again.
    Number of disappeared reservation increases every day. So we have to do Reconcile  again and again.

    When we used DHCP 2003 we have never had this problem.

    Thanks for any idea
    Jan Bezdek

    Friday, December 18, 2009 2:20 PM

All replies

  • Hello,


    Thank you for your post here.


    There is a known issue that scopes, options and reservations may disappear on Windows Server 2003 server. There is hotfix for Windows Server 2003 released for this issue in KB 936009.


    The "Lease duration for DHCP clients" option is set to 0 and some DHCP scope options disappear on a Windows Server 2003-based DHCP server


    For Windows Server 2008, I'd like to know how everything works if you restart the DHCP service. Meanwhile, please double check whether the reserved IP addresses are excluded in the DHCP scope.


    If the issue persists, we generally need to analyze the full memory dump files to locate the root cause. Unfortunately, debugging is beyond what we can do in the forum because of the nature of forum support. A support call to our product service team is needed for the debugging service. I'd like to recommend that you contact Microsoft Customer Support Service (CSS) for assistance so that this problem can be resolved efficiently. To obtain the phone numbers for specific technology request please take a look at the web site listed below:;EN-US;PHONENUMBERS


    If you are outside the US please see for regional support phone numbers. Thanks.





    Monday, December 21, 2009 10:42 AM
  • Thanks for your answer.  The restart DHCP service doesn’t solve the problem. The inconsistencies persist.

    We decided to rebuild the new DHCP database, we  used netsh ....

    I will post here the result.

    Have a nice day

    Tuesday, December 22, 2009 2:28 PM



    Thanks for the update.


    Please take your time to rebuild the DHCP service. If you have any questions or concerns, please do not hesitate to let us know. Thanks.



    Monday, December 28, 2009 9:49 AM
  •  Hi,
    we rebuilded DHCP server through the use of netsh commands.
    For the present the problem hasn't occured.
    We will see in the next days.
    Tuesday, December 29, 2009 9:26 AM
  • Hallo,

    ich got the same problem starting with the use of 2008R2. I´m running 4 networks-domains and the forget-reconsile-problem ist always the same.
    In the world of Server 2003 I always used 2 DHCP-Servers in one subnet because I want redundancy. The free adresses are not overlapping, but the 2 servers have the same client-reservation-adresses. Some clients like printers must have always the same adress. I had no problems for several years until I upgraded to 2008R2. Now I´m running a reconsile-script every hour. I helps, but that is NOT a good solution.
    Is there a bug in 2008R2?
    What does MS recommend in such a situation?

    Dresden, Germany
    • Proposed as answer by Dietmar54 Monday, January 11, 2010 10:40 AM
    Monday, January 11, 2010 10:39 AM
  • Hello,  
    it is exactly our problem.

    We could  notice that the most reservation which sometimes lost, have empty string in the dump file (netsh dhcp server a.b.c.d. dump ) in the field  Supported Types  - it is the last part in the raw with Reservation. The most Reservation have string “DHCP”, but the troubled reservation have the raw in the Dump file ended “” . So we repaired all raws for reserved address to end “DHCP” .  We removed DHCP role and we added  it again and we used repaired script for new configuration. It was  done  5 days ago and the problem hasn’t occurred up until now.

     I don’t  know if the problem is resolved forever and If yes where really  the problem was, but you can try it.

    Good luck


    Czech Republic

    Monday, January 11, 2010 12:35 PM
  • Hi

    We are having exactly the same problem, all our reservations are set as DHCP but they still go missing.

    We have also installed the DHCP server from scratch and manually entered everything instead of doing an import and this also has not helped.

    We also never had any issues like this with 2003 and are at a bit of a loss on how fix this as there not even anything in in either the dhcp logs or event logs that can help you. So if anyone has any suggestion it would be much appreciated becuase Dietmar quite correctlt says running reconciles every hour is not reall ya  solution


    Monday, January 11, 2010 3:37 PM
  • Hallo,

    thanks for your good ideas! I tried many of them since I use 2008R8 (August 09). Nothing helped for a longer time. If you use the long standard-lease-duration of 8 days, the problems may come in some weeks. I tried it in 4 subnets/domains/dhcp.
    I´m sure, the problem comes with the new "progressiv" features of 2008R2. When I started with 2 DHCPs with the same scope and non overlapping free adresses, the world was OK. The problem came with the first reservations - the same IPs at boths servers. Maybe that 2008R2 does not allow equal reservations on both DHCPs? MS always recommends the 80/20 rule with master- and standby slave-DHCP. Why is there no multi-master solution like DNS or Active Directory?
    I´m using 3 temporarely solutions - the users stopped crying:
       1. One DHCP 2008R2 and one 2003 in a subnet or
       2. Reconcile every hour by script or
       3. Keep using 2003 and wait for a better MS (ServicePack ?).

    I think, there is a bug in 2008R2. How can we ask Microsoft? Who has connections and can ask?

    • Proposed as answer by Dietmar54 Tuesday, January 12, 2010 8:49 AM
    Tuesday, January 12, 2010 8:21 AM
  • Hello,
     Have exact the same problem. We decided to upgrade our Domain Controllers from 2003 R2 to 2008 R2 (transition). Our problem is DHCP.
    After exporting settings on 2003 R2 and importing on 2008 R2 - reserved IPs disappear on first client's query. We can reconcile and verify, but it helps only for a short time. That takes place when DHCP server is running and authorized on both servers and also when it is running only on 2008 R2.

    I think it is a bug too.


    Tuesday, January 12, 2010 6:36 PM
  • Hi Guys

    I have used my EA to raise a call with PRS about this and I will let you know what the outcome of this is


    Tuesday, January 12, 2010 7:09 PM
  • Hi David,

    Did you receive any update on this yet? I'm really curious on how this is developing. Have the exact same issue right now and I want to make sure it's gone before I activate the scope.

    Thursday, January 14, 2010 10:46 AM
  • Hi

    I have a call in progress and its been elevated to the engineers as this does appear to be a bug in R2

    I'll let you know when its fixed as I would assume you'll all be able to get a hot fix for it when it is


    Thursday, January 14, 2010 11:36 AM
  • Hi David,

    Thanks for updating this thread! I'll await the outcome of your call.

    Regs, Arjan.
    Thursday, January 14, 2010 11:37 AM
  • Hallo David,

    what answer did your "call in progress" bring ???

    Tuesday, January 19, 2010 12:13 PM
  • Hi Dietmar,

    They are still working on a fix for this, they have acknowleged it's a bug and I am just waiting on them giving me the patch to fix it. Once I get the hotfix i let you know the knowledge base number so you can all find and download it fix your dhcp servers as well



    Tuesday, January 19, 2010 8:33 PM
  • Well, it's been another week... Any word from the MS engineers??

    Cheers, Arjan.
    Tuesday, January 26, 2010 9:08 AM
  • Unfortunately I am still waiting on a fix



    Saturday, January 30, 2010 10:43 AM
  • Thanks for letting us know!
    Monday, February 01, 2010 2:15 PM
  • Hi,

    do you have a Microsoft CASE-Number? We have exact the same problem and so I could add some importance to this case.

    Thanks Matt
    Tuesday, February 02, 2010 12:50 PM
  • Any updates anybody?
    Monday, February 08, 2010 2:01 PM
  • In March I´ll make a trip to Seattle and can visit Redmond and Microsoft. Is it possible to meet a member of the DHCP-team? Can you please give me a mail-address?

    Friday, February 12, 2010 10:14 AM
  • Received this update from Microsoft today.

    Dev is currently working on the issue. We have a private fix that we are testing that does solve the issue, but the test pass is going to be extensive, since this was an issue that was missed the first time around. Unfortunately I don't have an ETA as to when we will have a fix

    Tuesday, February 16, 2010 10:03 AM
  • I've logged it with MS as well, they've said pretty much the same as above.
    Tuesday, February 16, 2010 2:39 PM
  • Anybody heard anything yet on Hotfix release date?
    Monday, March 15, 2010 12:57 PM
  • 14th of April is the expected date for release to web is what I've heard from them.
    Monday, March 15, 2010 4:14 PM
  • Email from Microsoft support, so if anyone has logged a call you should get the fix soon.

    I finally have an update for the DHCP Issue you have been seeing. Dev has released a private in a test package form. I have placed the install package out on our external transfer site for you to download and test. This should be the final fix (binary wise) but there will be a different install package created for the April 14th release.

    Monday, March 22, 2010 9:23 AM
  • Looks like the rest of us are waiting until April 14th for the fix.  Eddie, if you do install the files from their transfer site, let us know if it does in fact fix the issue or not.
    Monday, March 22, 2010 12:40 PM
  • We have just recently migrated our DHCP services from 2000 to 2008 R2.  I soon noticed this problem too.  I have also been talking with a Tech and he too verified the April date for the Hotfix.  It does appear that a scheduled

    netsh dhcp server initiate reconcile fi

    about every 15 minutes will take care of the problem until the fix arrives.  Notice that I didn't use the 'fix' parameter at the end of that statement.  It seems the 'fix' parameter is also a bug.  Using 'fix' won't actually include a fix in the reconcile but anything else will.  So, the netsh command is broke too.

    Tuesday, March 23, 2010 8:51 PM
  • Tomorrow is suppose to be the day this fix is out.  Does anybody know what the KB article will be that had an official case open with Microsoft?
    Tuesday, April 13, 2010 2:38 PM
  • Hav not got the official KB yet but have been testing the fix and it certainly works for us so hopefully we will get the offocial fix tomorrow, i will post teh official kb if someone else with a case open for this does not get there first :)
    Wednesday, April 14, 2010 9:36 AM
  • Wednesday, April 14, 2010 4:09 PM
  • Thanks MJBIANCO,

    Installed this on all 3 of our DHCP servers.  Will watch closely over the next few days to see if our problem is fixed.  Hopefully no more problems!

    Thursday, April 15, 2010 1:36 AM
  • Thanks for posting the URL!

    Will get this installed asap and then hopefully will be able to use DHCP on R2 as it is supposed to be used :)

    Regs, Arjan.

    Thursday, April 15, 2010 7:24 AM
  • Please post back your results because I will be installing the hotfix next week on 2 DHCP boxes...
    Thursday, April 15, 2010 6:54 PM

    Microsoft Windows DHCP Team blog about this issue


    Monday, April 19, 2010 12:49 PM
  • How has anyone been doing with this hotfix?  I haven't had any new issues pop up, but I don't believe it's fixing the actual issue 100% of the time.  I'm going to apply it to more servers to see if I don't have a few "flukes" in the mix.


    Monday, April 26, 2010 4:44 PM
  • I haven't seen any issues since the installation of the hotfix on April 20th.

    I only use one DHCP server, so I can't test on others, but I'm very pleased with the results so far.

    Regs, Arjan.

    Thursday, April 29, 2010 1:17 PM
  • I am also using the hotfix for about a month in production enviroment. I use 2 windows 2008 r2 DHCP servers, and so far the issue seems to be resolved.
    Thursday, July 01, 2010 10:02 AM