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Questions about turning on scavenging and what static records to adjust RRS feed

  • Question

  • So i want to turn on scavenging and i have a few questions.

    1) my dns named dns entries for my domain controllers have their "Delete this record when it becomes stale" box unchecked.  But the "(same as parent)' record bound to the same IP and the domain controller has the "Delete this record when it becomes stale" CHECKED.  Do i need to uncheck that box on the "(same as parent)' record?

    2) is there a way to make it so when one of my client PCs goes from one network to another (and pulls a new IP) that it just automatically updates DNS and causes the old DNS record to be deleted?

    3) if the "No-Refresh Interval" and the "Refresh Interval" for scavenging are set for 7 days, how does the scavenging proccess work with a record that has existed for 15 days? Does the device that has that record need to keep updating that time stamp constantly so as to not get scavenged?  Like, does the pc need to check in with dns every 5 seconds or else it gets scavenged?

    Tuesday, September 12, 2017 6:31 PM

All replies

  • Hi Kavren,

    >>1) my dns named dns entries for my domain controllers have their "Delete this record when it becomes stale" box unchecked.  But the "(same as parent)' record bound to the same IP and the domain controller has the "Delete this record when it becomes stale" CHECKED.  Do i need to uncheck that box on the "(same as parent)' record?

    It depending on the how the resource record was originally added to the zone, do one of the following: 
    If the record was added dynamically using dynamic update, clear the Delete this record when it becomes stale check box to prevent its aging or potential removal during the scavenging process. If dynamic updates to this record continue to occur, the Domain Name System (DNS) server will always reset this check box so that the dynamically updated record can be deleted.

    If you added the record statically, select the Delete this record when it becomes stale check box to permit its aging or potential removal during the scavenging process.

    For your reference:

    Reset Aging and Scavenging Properties for a Specified Resource Record

    https://technet.microsoft.com/en-us/library/cc771570(v=ws.11).aspx

    >>is there a way to make it so when one of my client PCs goes from one network to another (and pulls a new IP) that it just automatically updates DNS and causes the old DNS record to be deleted?

    Please select the Always dynamically update DNS records check box and Discard A and PTR records when lease id deleted check box.

    >>3) if the "No-Refresh Interval" and the "Refresh Interval" for scavenging are set for 7 days, how does the scavenging proccess work with a record that has existed for 15 days? Does the device that has that record need to keep updating that time stamp constantly so as to not get scavenged?  Like, does the pc need to check in with dns every 5 seconds or else it gets scavenged?

    If the value of this sum(14) is greater than current server time, no action is taken and the record continues to age in the zone.

    If the value of this sum(14) is less than current server time(15), the record is deleted.

    For more details, please refer to the following link:

    Understanding Aging and Scavenging

    https://technet.microsoft.com/en-us/library/cc771677(v=ws.11).aspx

    Best Regards,

    Candy


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    Wednesday, September 13, 2017 7:22 AM
  • What is the (same as parent) dns record [which is bound to the same IP and my Domain Controller], and more overe, what happens if it is deleted?  The record is: (same as parent), Host (A), IP=DomainControllerIP


    is there a reason *not* to check "Always dynamically update DNS records"? if so, what is it?

    Also, im confused about the scavenging formula. 

    If the current time is 1pm, and the sum of the Record time stamp + No-refresh interval for zone + Refresh interval for zone
    are as follows 2pm + 7days + 7days, then its 13hours vs 62 hours.  Won't the "Record time stamp + No-refresh interval for zone + Refresh interval for zone" always be greater than the current time?  The current time can only be a maximum of 24 (24 hours in a day) where as the other formula is measured in multiple days.
    • Edited by Kavren Wednesday, September 13, 2017 3:28 PM
    Wednesday, September 13, 2017 2:56 PM
  • Hi Kavren,

    >>What is the (same as parent) dns record [which is bound to the same IP and my Domain Controller], and more overe, what happens if it is deleted?  The record is: (same as parent), Host (A), IP=DomainControllerIP

    For the A record, that is created automatically by the domain controllerr's Netlogon service. Each DC's netlogon service will create one, This record is actually called the LdapIpAddress and is used by various AD services, such as DFS, the GetGpoList function, etc.

    The "same as parent" LdapIpAddress record CANNOT be altered if this zone is for an Active Directory zone.

    For your reference:

    DNS - (same as parent folder) - issue and question

    https://social.technet.microsoft.com/Forums/windowsserver/en-US/4e08886c-c697-4469-925e-b2d3a4a8d199/dns-same-as-parent-folder-issue-and-question?forum=winserverDS

    >>If the current time is 1pm, and the sum of the Record time stamp + No-refresh interval for zone + Refresh interval for zone
    are as follows 2pm + 7days + 7days, then its 13hours vs 62 hours.  Won't the "Record time stamp + No-refresh interval for zone + Refresh interval for zone" always be greater than the current time?  The current time can only be a maximum of 24 (24 hours in a day) where as the other formula is measured in multiple days.

    Please check if you could understand by following image:

    For example,if the record time stamp is 9/14/2017 1:00:00 pm.

    If the record is updated in this period, the sum will change.

    Best Regards,

    Candy


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    Thursday, September 14, 2017 3:16 AM
  • Hi Kavren,

    Just checking in to see if the information provided was helpful.

    Please let us know if you would like further assistance.

    Best Regards,

    Candy


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    Monday, September 18, 2017 9:28 AM
  • Hi Kavren,

    Did you have any updates?

    Best Regards,

    Candy


    Please remember to mark the replies as answers if they help.
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    Tuesday, September 26, 2017 6:09 AM