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Stop systems with fixed IP addresses getting DHCP one as well

    Question

  • I'm testing IPv6

    I have got my DHCP server giving out addresses.

    How do I stop it giving extra addresses to servers which have already got a fixed address?

    Probably I'm looking for a GPO to stop the servers asking for an IP address.


    CarolChi

    Thursday, July 25, 2013 2:40 PM

All replies

  • I too have seen this on W2K8-R2.

    If I disable the "M" and "O" flags -and- set to persistent for a specific interface on the server, and the command is ack'd as "Ok", the server doesn't abide by that setting.

    According to info on the server, if the "...router discovery flag is enabled and the advertising flag is disabled, then changing the M & O flags has no affect..."

    So, I disabled: router discovery, M flag, and O flag, and now the W2K8R2 srvr does not do Stateful address autoconfig (DHCPv6).

    HOWEVER, with router discovery disable, the server no longer gets its IPv6 default gateway from the RA.....really bad now. (since the DHCPv6 standard has no provision for a default gateway option [at least not yet])

    If you simply set router discovery to enable, then the M & O flags also go to enable (even though you don't "do that").

    So, I do not have the answer, I merely wanted to provide what I had observed.

    Hopefully, someone else knows more.


    Jeff Carrell

    Thursday, July 25, 2013 4:36 PM
  • Thanks for that. So if we could find a way of telling the machine what router to use we would be OK...

    I don't like all this automatic stuff.


    CarolChi

    Thursday, July 25, 2013 6:19 PM
  • I'm not clear where and how to disable these flags.

    Can anyone help?

    In my test environment I have given all my servers fixed IP addresses (thinking I can them use these to limit access in my firewall) - for example an internal app server can only access and be accessed from the app server provider, and I can turn this on or off depending on whether I need support at the moment or not.

     


    CarolChi

    Friday, July 26, 2013 5:37 PM
  • Still finding that after each reboot I have an extra DHCP assigned IPv6 address on each system. They go away if I do ipconfig /release6, but they mess up my DHCP and make any kind of logging hard to do.

    And on some systems (including DCs and DHCP servers I am getting a DHCP address INSTEAD of the fixed IP address I have assigned to the system.


    CarolChi


    Monday, July 29, 2013 5:57 AM