COMMAND

    DHCP Manager v4

SYSTEMS AFFECTED

    Win NT 3.51, 4.0

PROBLEM

    Thanks to  'firesign' for  pointing out  this to  me.   Basically,
    there is a bug in MS DHCP Manager that will allow for 2 IPs to  be
    leased  to  one  machine.   In  network  environments  that  allow
    duplicate routes between  DHCP clients and  a DHCP server,  a DHCP
    server gives out one IP address to two different clients.

    The cause of this behavior is that, in some cases, the  processing
    of  the  second  Discover  packet  causes  the  server  to set the
    address state of the address from leased to offered when the  DHCP
    Server sends the  second Offer. The  client will not  reply to the
    second Offer, because it already has an active lease. Because  the
    DHCP Server does not receive  a Request packet in response  to the
    Offer,  the  lease  on  the  Offered  address will timeout and the
    address  will  be  placed  back  into  the  pool  of  IP addresses
    available for lease.

    This problem may occur in several different network  environments,
    including Token  Ring environments  with large  numbers of  source
    routing bridges (where the bridges would  be set up in a way  that
    would  provide  multiple,  unique  routes  between  the server and
    client) and  Ethernet environments  with multiple  routers enabled
    with BOOTP relay agents or IP helper addressing.

SOLUTION

    This was corrected with SP3 (NT4.0) or SP5 (NT3.51).