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DHCP Reservation is disappearing. RRS feed

  • Question

  •  There is problem with reservation that part of reservation disappears and endpoint devices cannot get network connection. When try to recreate reservation it says cannot use specific address and then old reservation appears.

    This issue has been placed couple months and couple of weeks ago server rebooted, but issue is continuing. Today again I made "fix" that tried to re-create reservation and now it works again.

    Can anyone tell why this disappears for a while?


    Sugandh

    Tuesday, August 23, 2016 10:25 AM

Answers

  • Hi Sugandh,

    >>When DHCP reservation is disappeared for a while, it means reservation is deleted or not?

    No, if it has deleted, reservation did not appear when you recreate reservation.

    You could run SFC /scannow command to check system file was correct.

    >>DHCP Reservation status will be in inactive state for some time and he tried to recreate same reservation with same IP,MAc address and again status will be in active state

    The status means that address not in use.

    >>Can we use the IP's which are in excluded range? The IP assigned to DHCP client is in excluded range.

    Even if reservation address was not in exclude range, DHCP server will not assign it to other computers.

    Best Regards

    John


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    Thursday, August 25, 2016 5:14 AM

All replies

  • Hi

     First you should check event viewer menu for related error log's.Also you can use "DHCP Server Events Tool" for advanced logging;

    DHCP Server Events Tool ; https://blogs.technet.microsoft.com/teamdhcp/2009/03/20/dhcp-server-events-tool/

    And chek this for "How to monitor and audit DHCP Server configuration changes for compliance"

    https://blogs.technet.microsoft.com/teamdhcp/2009/03/03/how-to-monitor-and-audit-dhcp-server-configuration-changes-for-compliance/


    This posting is provided AS IS with no warranties or guarantees,and confers no rights. Best regards Burak Uğur

    Tuesday, August 23, 2016 10:31 AM
  • Can we use the IP's which are in excluded range for DHCP reservations?The Ip set to client is in exclude range. In Lease Section status of reservation is in inactive state for some time and again after sometime it will get active. Is there any issue regarding Ip's and any issue from DHCP client system.

    Sugandh



    Wednesday, August 24, 2016 5:55 AM
  • Hi Sugandh,

    I appreciate that you could provide event of issue, that will help us to provide further helpful solution for you.

    What is the operation system of DHCP server?

    If it is windows 2008, there has a similar issue with yours.

    DHCP 2008R2- Reservation are disappearing

    https://social.technet.microsoft.com/Forums/windowsserver/en-US/5f0872d9-ff50-4ce9-a001-d9f7ab8cc4c6/dhcp-2008r2-reservation-are-disappearing?forum=winserverNIS

    DHCP Servers in Windows Server 2008r2 are deleting reservations, in certain instances, without user intervention.

    You could check the article to confirm that you have configuration of scope as link said:

    DHCP Server deletes reservations

    https://blogs.technet.microsoft.com/teamdhcp/2010/04/19/dhcp-server-deletes-reservations/

    Best Regards

    John


    Please remember to mark the replies as an answers if they help and unmark them if they provide no help.
    If you have feedback for TechNet Subscriber Support, contact tnmff@microsoft.com.

    Wednesday, August 24, 2016 6:36 AM
  • Windows server 2008 R2 is the operating system of DHCP server and I didn't find any log or event id regarding this issue.

    The main issue is in lease section. DHCP Reservation status will be in inactive state for some time and he tried to recreate same reservation with same IP,MAc address and again status will be in active state.

     I have some doubts on below mentioned points.

    1. When DHCP reservation is disappeared for a while, it means reservation is deleted or not?

    2. If it is not deleted, any modification of previous DHCP reservation doesn't help anything. The only way is to delete reservation and again we need to create it.

    3. Can we use the IP's which are in excluded range? The IP assigned to DHCP client is in excluded range. Will be there any issue using excluded IP for reservation may be that's why DHCP "reservation(Inactive)" status will occur for a while?


    Sugandh

    Wednesday, August 24, 2016 9:39 AM
  • Hi Sugandh,

    >>When DHCP reservation is disappeared for a while, it means reservation is deleted or not?

    No, if it has deleted, reservation did not appear when you recreate reservation.

    You could run SFC /scannow command to check system file was correct.

    >>DHCP Reservation status will be in inactive state for some time and he tried to recreate same reservation with same IP,MAc address and again status will be in active state

    The status means that address not in use.

    >>Can we use the IP's which are in excluded range? The IP assigned to DHCP client is in excluded range.

    Even if reservation address was not in exclude range, DHCP server will not assign it to other computers.

    Best Regards

    John


    Please remember to mark the replies as an answers if they help and unmark them if they provide no help.
    If you have feedback for TechNet Subscriber Support, contact tnmff@microsoft.com.

    Thursday, August 25, 2016 5:14 AM