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Laptops - DNS / DHCP automatic updates RRS feed

  • Question

  • Hello all,

    I was hired to small company where we run some linux servers and 1 windows server with AD, DNS, DHCP.

    Current situation:
    DHCP scope range is: 10.2.14.1 - 10.2.14.254 /24
    every laptop has 1 reservation (which is not good solution imho) 
    There are also personal devices served.

    This causes troubles with laptops backups which is configured for IPs and there is also a mess in DNS records. (backup program can use domain names)

    I would like to make laptops reachable by it's domain name regardless it's on WLAN or ETHernet.

    Could you please advice me what to do in order to achieve that?

    I have read something about automatic DNS records updates with DHCP, mabye scavenging.
    Also increasing the pool.
    All suggestions welcome incl. readings, videos, implementations, solutions.

    Thanks
    Jan.

     


    • Edited by oglop Friday, August 19, 2016 11:25 AM
    Friday, August 19, 2016 11:24 AM

Answers

  • First, your DHCP is running on a Domain Controller which require a specific configuration on your DHCP Server.  Be sure to specify an "Alternate Credentials" otherwise you could have some issues (Properties of IPv4, then Advanced Tab.

    ref: https://blogs.technet.microsoft.com/stdqry/2012/04/03/dhcp-server-in-dcs-and-dns-registrations/

    Then, in your DHCP, the default settings is "Dynamically update DNS Record if requested by the DHCP clients" and "Discard A and PTR records when lease is deleted.  These options should be enough.

    Personally, I would remove the IP reservations and let the computer get his IP dynamically (personal choice).  When the laptop will connect using his Eth card, it will get a specific IP Address and if you connect with WiFi, it will get another IP Address (DHCP Address are assigned by MAC address) but in the DNS, it should not cause any issue.

    By default, when you create a new Domain, the DNS zone is set to Dynamic Updates "Secure Only".  This mean that the client computer must be member of the domain to update the DNS (this may cause issue with Personal devices that are not member of the domain).

    Aging / Scavenging is another thing... You should enable it if you want to keep a clean DNS Zone.  It will cleanup obsolete DNS records based on the timestamp of the record.  The default settings is 7 days for aging and 7 days for scavenging.  You can decrease the aging / scavenging time if you want but I would not define a value (aging + scavenging) lower than half of the DHCP scope.

    Here is a good article that explain the process

    http://social.technet.microsoft.com/wiki/contents/articles/21724.how-dns-aging-and-scavenging-works.aspx

    hth


    This posting is provided AS IS without warranty of any kind

    • Proposed as answer by Todd Heron Friday, August 19, 2016 2:54 PM
    • Marked as answer by Leo HanModerator Wednesday, September 7, 2016 7:09 AM
    Friday, August 19, 2016 12:58 PM

All replies

  • First, your DHCP is running on a Domain Controller which require a specific configuration on your DHCP Server.  Be sure to specify an "Alternate Credentials" otherwise you could have some issues (Properties of IPv4, then Advanced Tab.

    ref: https://blogs.technet.microsoft.com/stdqry/2012/04/03/dhcp-server-in-dcs-and-dns-registrations/

    Then, in your DHCP, the default settings is "Dynamically update DNS Record if requested by the DHCP clients" and "Discard A and PTR records when lease is deleted.  These options should be enough.

    Personally, I would remove the IP reservations and let the computer get his IP dynamically (personal choice).  When the laptop will connect using his Eth card, it will get a specific IP Address and if you connect with WiFi, it will get another IP Address (DHCP Address are assigned by MAC address) but in the DNS, it should not cause any issue.

    By default, when you create a new Domain, the DNS zone is set to Dynamic Updates "Secure Only".  This mean that the client computer must be member of the domain to update the DNS (this may cause issue with Personal devices that are not member of the domain).

    Aging / Scavenging is another thing... You should enable it if you want to keep a clean DNS Zone.  It will cleanup obsolete DNS records based on the timestamp of the record.  The default settings is 7 days for aging and 7 days for scavenging.  You can decrease the aging / scavenging time if you want but I would not define a value (aging + scavenging) lower than half of the DHCP scope.

    Here is a good article that explain the process

    http://social.technet.microsoft.com/wiki/contents/articles/21724.how-dns-aging-and-scavenging-works.aspx

    hth


    This posting is provided AS IS without warranty of any kind

    • Proposed as answer by Todd Heron Friday, August 19, 2016 2:54 PM
    • Marked as answer by Leo HanModerator Wednesday, September 7, 2016 7:09 AM
    Friday, August 19, 2016 12:58 PM
  • Hi,

    Just want to confirm the current situations.

    Please feel free to let us know if you need further assistance.

    Best Regards

    John


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    • Edited by John Lii Tuesday, September 6, 2016 8:26 AM
    Tuesday, September 6, 2016 8:23 AM