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negative acknowledgement to a dhcp server

Discussion in 'Networking' started by donnj, Apr 3, 2008.

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  1. donnj

    donnj Thread Starter

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    How do I Force a client computer to send a negative acknowledgement to a dhcp server ?
     
  2. Wanderer2

    Wanderer2

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    Assign it a static ip instead of autoassigned. Though that is not a negative but no dhcp request

    I don't believe the client ever sends a negative acknowledgement but the dhcp server does when it has run out of available ips.
     
  3. JohnWill

    JohnWill Retired Moderator

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    Actually, the client can send a NAK under certain circumstances. One being if the client requests a specific IP address or requires some specific settings from the DHCP server, and the offer packet mismatches the requirements, the client will decline the offer.

     
  4. Wanderer2

    Wanderer2

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    That would be a decline not a nak.
    http://www.isoc.org/HMP/PAPER/127/html/paper.html

    Still comes down to I don't know of any way to " Force a client computer to send a negative acknowledgement to a dhcp server "

    I don't think its possble. Do you JohnWill?
     
  5. JohnWill

    JohnWill Retired Moderator

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    OK, it's a decline and not a NAK, I knew it could refuse the offer.
     
  6. donnj

    donnj Thread Starter

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    thanks to all for the replys. basically heres the senerio. I have an end user that that is getting an Ip address conflict. advised user to to release and renew. despite this we keep getting the same ip address and without having access to the DHCP server we want to force the dhcp client to ask for a different IP address
     
  7. JohnWill

    JohnWill Retired Moderator

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    One of the following things are probably happening.

    1. The DHCP server is not attempting to ping the address before assigning it, and it has no record of that address being assigned.
    2. The IP address in question is assigned to a computer or device that doesn't respond to PING requests.
    3. The IP address in question has been statically assigned within the range of the DHCP server pool.

    For SOHO routers, duplicate IP addresses are frequently caused by restarting the router without restarting ALL of the attached workstations and other TCP/IP connected devices.
     
  8. donnj

    donnj Thread Starter

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    Thanks for the input the three possibilities have been exausted SR analyst problem now :(y)
     
  9. JohnWill

    JohnWill Retired Moderator

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    Pass the buck, my favorite solution! :D
     
  10. donnj

    donnj Thread Starter

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    thanks for the help Sr analyst considering packet manipulation for this point fwd consider thuis issue Solved
     
  11. JohnWill

    JohnWill Retired Moderator

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    You can mark your own threads solved using the thread tools at the top of the page in the upper right corner.© :)

    [​IMG]
     
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