Weird DHCP Thing - Network

This is a discussion on Weird DHCP Thing - Network ; For the past year or so, I have had the same Dynamically Assigned IP address from Comcast. For whatever reason, the DHCP lease always renewed (or re-established after being off for a while) with the same IP. Today, I installed ...

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Thread: Weird DHCP Thing

  1. Weird DHCP Thing

    For the past year or so, I have had the same Dynamically Assigned IP address
    from Comcast. For whatever reason, the DHCP lease always renewed (or
    re-established after being off for a while) with the same IP. Today, I
    installed a router between my PC and the Cable Modem. Suddenly the IP for
    the WAN side of the router is Different than the IP I've had for so long.
    (No, I'm not talking about the NAT LAN-side IP.) Is it just bizarre
    coincidence that it changed right when I installed the router? I mean, how
    could Comcast's DHCP server know about the router, and why would it care
    anyway? TIA.
    ---Mick



  2. Re: Weird DHCP Thing

    Mick said in news:UrKdnd0cEdpj0wHdRVn-ug@comcast.com:
    > For the past year or so, I have had the same Dynamically Assigned IP
    > address from Comcast. For whatever reason, the DHCP lease always
    > renewed (or re-established after being off for a while) with the same
    > IP. Today, I installed a router between my PC and the Cable Modem.
    > Suddenly the IP for the WAN side of the router is Different than the
    > IP I've had for so long. (No, I'm not talking about the NAT LAN-side
    > IP.) Is it just bizarre coincidence that it changed right when I
    > installed the router? I mean, how could Comcast's DHCP server know
    > about the router, and why would it care anyway? TIA.
    > ---Mick


    Did you use the option with your NAT router to clone the MAC address of your
    computer's network card before connecting the router to the cable modem (so
    the router looks like the same hardware as your network card)?

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  3. Re: Weird DHCP Thing

    No, I didn't. Should I? What happens if I do/don't?

    "*Vanguard*" wrote in message
    news:YoqdnZYAFZ-vwgHdRVn_iw@comcast.com...
    > Mick said in news:UrKdnd0cEdpj0wHdRVn-ug@comcast.com:
    > > For the past year or so, I have had the same Dynamically Assigned IP
    > > address from Comcast. For whatever reason, the DHCP lease always
    > > renewed (or re-established after being off for a while) with the same
    > > IP. Today, I installed a router between my PC and the Cable Modem.
    > > Suddenly the IP for the WAN side of the router is Different than the
    > > IP I've had for so long. (No, I'm not talking about the NAT LAN-side
    > > IP.) Is it just bizarre coincidence that it changed right when I
    > > installed the router? I mean, how could Comcast's DHCP server know
    > > about the router, and why would it care anyway? TIA.
    > > ---Mick

    >
    > Did you use the option with your NAT router to clone the MAC address of

    your
    > computer's network card before connecting the router to the cable modem

    (so
    > the router looks like the same hardware as your network card)?
    >
    > --
    > __________________________________________________ __________
    > *** Post replies to newsgroup. Share with others.
    > *** Email: domain = ".com" and append "=NEWS=" to Subject.
    > __________________________________________________ __________
    >




  4. Re: Weird DHCP Thing

    Mick said in news:dPWdnXP6xJsO_gHdRVn-sA@comcast.com:
    > No, I didn't. Should I? What happens if I do/don't?


    Since your router with a different MAC address looks like a different
    computer than your actual computer, and since the DHCP-assigned IP address
    to your actual computer had probably not yet expired, your ISP's DHCP server
    had to assign another IP address to your router. The same would have
    occurred if you had used a hub or switch instead of a router and connected a
    second computer.


  5. Re: Weird DHCP Thing

    Thanks! I sort of guessed that might be the case after thinking about it a
    while longer, so then I cloned the MAC, and sure enough, got the old IP
    back.

    "*Vanguard*" wrote in message
    news:WPydnYkhgJSIbwHdRVn-gw@comcast.com...
    > Mick said in news:dPWdnXP6xJsO_gHdRVn-sA@comcast.com:
    > > No, I didn't. Should I? What happens if I do/don't?

    >
    > Since your router with a different MAC address looks like a different
    > computer than your actual computer, and since the DHCP-assigned IP address
    > to your actual computer had probably not yet expired, your ISP's DHCP

    server
    > had to assign another IP address to your router. The same would have
    > occurred if you had used a hub or switch instead of a router and connected

    a
    > second computer.
    >




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