DHCP Leasing

Discussion in 'MCSE' started by =?Utf-8?B?Zm1zbWNzZQ==?=, Nov 20, 2005.

  1. Client01 one leases an IP and so does Client02.
    One hour after their leasing, the DHCP server goes down.
    Client01 and Client02 have to reboot for any reason.

    After rebooting, Client01 maintains its IP address, as per the leasing
    expiration. Client02 releases the IP (remember they both have the same
    leasing period) for some reason.

    Both clients are Windows XP, and their behavior is expected to be the same,
    since they have the same TCP/IP configuration. They are in the same subnet
    and both can find the default gateway. No alternate IP is assigned.

    Any clue about why Client02 would release its IP before the leasing time
    expires?
    Remember Client01 has the same config and does not release the IP.
     
    =?Utf-8?B?Zm1zbWNzZQ==?=, Nov 20, 2005
    #1
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  2. =?Utf-8?B?Zm1zbWNzZQ==?=

    Ben Smith Guest

    In article <>,
    says...
    > Client01 one leases an IP and so does Client02.
    > One hour after their leasing, the DHCP server goes down.
    > Client01 and Client02 have to reboot for any reason.
    >
    > After rebooting, Client01 maintains its IP address, as per the leasing
    > expiration. Client02 releases the IP (remember they both have the same
    > leasing period) for some reason.
    >
    > Both clients are Windows XP, and their behavior is expected to be the same,
    > since they have the same TCP/IP configuration. They are in the same subnet
    > and both can find the default gateway. No alternate IP is assigned.
    >
    > Any clue about why Client02 would release its IP before the leasing time
    > expires?
    > Remember Client01 has the same config and does not release the IP.


    This is not quite how DHCP leases work. DHCP leases are controlled by
    the DHCP server, not the client.

    When a DHCP client reboots, after the IP stack is started, it issues a
    DCHP Discovery packet, if the DHCP servers that receive the broadcast
    respond with a Acknowledge packet. If the DHCP server that acknowledges
    the client was the one that issued the address the client has cached,
    the client will request it in the Request packet, if the lease is still
    active, the DHCP server will respond with a Offer package for the
    address and the lease time is reset.

    If the DHCP server is not online when the client reboots, the client
    will use an APIPA address and continue to rebroadcast a Discovery packet
    every 5 minutes (2000 and later).

    As for why the two XP clients are behaving differntly, my guess is that
    the network IP properties on each client are configured differently.
    Most likely, APIPA is turned off on Client01. Client02 is working as
    expected.

    If you would like to learn more about this I suggest reading the RFC on
    DHCP (while boring as heck, if there is no better source for learning
    DHCP, which is a pretty simple protocol) and/or installing a network
    monitor and watching DHCP traffic.
     
    Ben Smith, Nov 20, 2005
    #2
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  3. Wonder the following situation, you've centralized your IP distribution in a
    main site and several sites, let's say 15 sites, all depend on the main one
    to get an IP.

    All clients in the 15 sites have gotten an IP early in the morning and then
    at midday the link goes down for all 15 sites to the main site and, as you
    are lucky enough, there's a power down in those 15 sites.
    By what you explained, all the clients would get an APIPA then...??

    "Ben Smith" wrote:

    > In article <>,
    > says...
    > > Client01 one leases an IP and so does Client02.
    > > One hour after their leasing, the DHCP server goes down.
    > > Client01 and Client02 have to reboot for any reason.
    > >
    > > After rebooting, Client01 maintains its IP address, as per the leasing
    > > expiration. Client02 releases the IP (remember they both have the same
    > > leasing period) for some reason.
    > >
    > > Both clients are Windows XP, and their behavior is expected to be the same,
    > > since they have the same TCP/IP configuration. They are in the same subnet
    > > and both can find the default gateway. No alternate IP is assigned.
    > >
    > > Any clue about why Client02 would release its IP before the leasing time
    > > expires?
    > > Remember Client01 has the same config and does not release the IP.

    >
    > This is not quite how DHCP leases work. DHCP leases are controlled by
    > the DHCP server, not the client.
    >
    > When a DHCP client reboots, after the IP stack is started, it issues a
    > DCHP Discovery packet, if the DHCP servers that receive the broadcast
    > respond with a Acknowledge packet. If the DHCP server that acknowledges
    > the client was the one that issued the address the client has cached,
    > the client will request it in the Request packet, if the lease is still
    > active, the DHCP server will respond with a Offer package for the
    > address and the lease time is reset.
    >
    > If the DHCP server is not online when the client reboots, the client
    > will use an APIPA address and continue to rebroadcast a Discovery packet
    > every 5 minutes (2000 and later).
    >
    > As for why the two XP clients are behaving differntly, my guess is that
    > the network IP properties on each client are configured differently.
    > Most likely, APIPA is turned off on Client01. Client02 is working as
    > expected.
    >
    > If you would like to learn more about this I suggest reading the RFC on
    > DHCP (while boring as heck, if there is no better source for learning
    > DHCP, which is a pretty simple protocol) and/or installing a network
    > monitor and watching DHCP traffic.
    >
     
    =?Utf-8?B?Zm1zbWNzZQ==?=, Nov 21, 2005
    #3
  4. =?Utf-8?B?Zm1zbWNzZQ==?=

    LRM Guest

    Answers in line
    "fmsmcse" <> Persisted in message
    news:...
    > Client01 one leases an IP and so does Client02.
    > One hour after their leasing, the DHCP server goes down.


    Your DHCP server going down would trouble me most.

    > Client01 and Client02 have to reboot for any reason.
    >
    > After rebooting, Client01 maintains its IP address, as per the leasing
    > expiration. Client02 releases the IP (remember they both have the same
    > leasing period) for some reason.
    >
    > Both clients are Windows XP, and their behavior is expected to be the
    > same,
    > since they have the same TCP/IP configuration. They are in the same subnet
    > and both can find the default gateway. No alternate IP is assigned.
    >
    > Any clue about why Client02 would release its IP before the leasing time
    > expires?


    Nocturnal gave you a clue last week when he asked if your DHCP client
    service was disabled.
    Check that this service is working properly (remember to check the services
    it depends on as well). If it fails to start in a timely manner your ip
    address will become 0.0.0.0 and if the service comes on line a few moments
    later your macine will begin to look for the DHCP server asking for an IP
    address. When no response is received Client02 will give itself an APIPA.

    > Remember Client01 has the same config and does not release the IP.


    TCP/IP configs may be the same, but services and other hardware may not be
    equal.

    As for the question of the dhcp info remaining after reboot on Client01, the
    registry holds the answer to this please see:
    http://support.microsoft.com/default.aspx?scid=kb;en-us;314053

    If you continue to have trouble please post in:
    microsoft.public.windows.server.networking group.


    LRM
    ....and answer came there none -- and that was scarcely odd because they'd
    eaten everyone.
    ~Lewis Carroll: Through the Looking Glass
     
    LRM, Nov 21, 2005
    #4
  5. =?Utf-8?B?Zm1zbWNzZQ==?=

    Ben Smith Guest

    In article <>,
    says...
    > Wonder the following situation, you've centralized your IP distribution in a
    > main site and several sites, let's say 15 sites, all depend on the main one
    > to get an IP.
    >
    > All clients in the 15 sites have gotten an IP early in the morning and then
    > at midday the link goes down for all 15 sites to the main site and, as you
    > are lucky enough, there's a power down in those 15 sites.
    > By what you explained, all the clients would get an APIPA then...??


    Exactly. And this is one of the exact scenarios APIPA was designed for,
    because in this scenario all of the hosts would be able communicate with
    each other in the APIPA address space.

    >
    > "Ben Smith" wrote:
    >
    > > In article <>,
    > > says...
    > > > Client01 one leases an IP and so does Client02.
    > > > One hour after their leasing, the DHCP server goes down.
    > > > Client01 and Client02 have to reboot for any reason.
    > > >
    > > > After rebooting, Client01 maintains its IP address, as per the leasing
    > > > expiration. Client02 releases the IP (remember they both have the same
    > > > leasing period) for some reason.
    > > >
    > > > Both clients are Windows XP, and their behavior is expected to be the same,
    > > > since they have the same TCP/IP configuration. They are in the same subnet
    > > > and both can find the default gateway. No alternate IP is assigned.
    > > >
    > > > Any clue about why Client02 would release its IP before the leasing time
    > > > expires?
    > > > Remember Client01 has the same config and does not release the IP.

    > >
    > > This is not quite how DHCP leases work. DHCP leases are controlled by
    > > the DHCP server, not the client.
    > >
    > > When a DHCP client reboots, after the IP stack is started, it issues a
    > > DCHP Discovery packet, if the DHCP servers that receive the broadcast
    > > respond with a Acknowledge packet. If the DHCP server that acknowledges
    > > the client was the one that issued the address the client has cached,
    > > the client will request it in the Request packet, if the lease is still
    > > active, the DHCP server will respond with a Offer package for the
    > > address and the lease time is reset.
    > >
    > > If the DHCP server is not online when the client reboots, the client
    > > will use an APIPA address and continue to rebroadcast a Discovery packet
    > > every 5 minutes (2000 and later).
    > >
    > > As for why the two XP clients are behaving differntly, my guess is that
    > > the network IP properties on each client are configured differently.
    > > Most likely, APIPA is turned off on Client01. Client02 is working as
    > > expected.
    > >
    > > If you would like to learn more about this I suggest reading the RFC on
    > > DHCP (while boring as heck, if there is no better source for learning
    > > DHCP, which is a pretty simple protocol) and/or installing a network
    > > monitor and watching DHCP traffic.
    > >

    >
     
    Ben Smith, Nov 21, 2005
    #5
  6. =?Utf-8?B?Zm1zbWNzZQ==?=

    kpg Guest

    Ben Smith <> said something like

    > # Name resolution details: file://c:\temp\178306.htm (11/21/2005
    > 9:25:50 AM) # In article
    > <>,
    > says...
    >> Client01 one leases an IP and so does Client02.
    >> One hour after their leasing, the DHCP server goes down.
    >> Client01 and Client02 have to reboot for any reason.
    >>
    >> After rebooting, Client01 maintains its IP address, as per the
    >> leasing expiration. Client02 releases the IP (remember they both have
    >> the same leasing period) for some reason.
    >>
    >> Both clients are Windows XP, and their behavior is expected to be the
    >> same, since they have the same TCP/IP configuration. They are in the
    >> same subnet and both can find the default gateway. No alternate IP is
    >> assigned.
    >>
    >> Any clue about why Client02 would release its IP before the leasing
    >> time expires?
    >> Remember Client01 has the same config and does not release the IP.

    >
    > This is not quite how DHCP leases work. DHCP leases are controlled by
    > the DHCP server, not the client.
    >
    > When a DHCP client reboots, after the IP stack is started, it issues a
    > DCHP Discovery packet, if the DHCP servers that receive the broadcast
    > respond with a Acknowledge packet. If the DHCP server that
    > acknowledges the client was the one that issued the address the client
    > has cached, the client will request it in the Request packet, if the
    > lease is still active, the DHCP server will respond with a Offer
    > package for the address and the lease time is reset.
    >
    > If the DHCP server is not online when the client reboots, the client
    > will use an APIPA address and continue to rebroadcast a Discovery
    > packet every 5 minutes (2000 and later).
    >
    > As for why the two XP clients are behaving differntly, my guess is
    > that the network IP properties on each client are configured
    > differently. Most likely, APIPA is turned off on Client01. Client02 is
    > working as expected.


    Collect me if I'm long, but it seems the bottom line is that Clinet02
    cannot see the network (or at least the DHCP Server).

    kpg
     
    kpg, Nov 21, 2005
    #6
  7. =?Utf-8?B?Zm1zbWNzZQ==?=

    Ben Smith Guest

    In article <Xns9715603DF66Bipostthereforeiam@127.0.0.1>,
    ipost@thereforeiam says...
    > Ben Smith <> said something like
    >
    > > # Name resolution details: file://c:\temp\178306.htm (11/21/2005
    > > 9:25:50 AM) # In article
    > > <>,
    > > says...
    > >> Client01 one leases an IP and so does Client02.
    > >> One hour after their leasing, the DHCP server goes down.
    > >> Client01 and Client02 have to reboot for any reason.
    > >>
    > >> After rebooting, Client01 maintains its IP address, as per the
    > >> leasing expiration. Client02 releases the IP (remember they both have
    > >> the same leasing period) for some reason.
    > >>
    > >> Both clients are Windows XP, and their behavior is expected to be the
    > >> same, since they have the same TCP/IP configuration. They are in the
    > >> same subnet and both can find the default gateway. No alternate IP is
    > >> assigned.
    > >>
    > >> Any clue about why Client02 would release its IP before the leasing
    > >> time expires?
    > >> Remember Client01 has the same config and does not release the IP.

    > >
    > > This is not quite how DHCP leases work. DHCP leases are controlled by
    > > the DHCP server, not the client.
    > >
    > > When a DHCP client reboots, after the IP stack is started, it issues a
    > > DCHP Discovery packet, if the DHCP servers that receive the broadcast
    > > respond with a Acknowledge packet. If the DHCP server that
    > > acknowledges the client was the one that issued the address the client
    > > has cached, the client will request it in the Request packet, if the
    > > lease is still active, the DHCP server will respond with a Offer
    > > package for the address and the lease time is reset.
    > >
    > > If the DHCP server is not online when the client reboots, the client
    > > will use an APIPA address and continue to rebroadcast a Discovery
    > > packet every 5 minutes (2000 and later).
    > >
    > > As for why the two XP clients are behaving differntly, my guess is
    > > that the network IP properties on each client are configured
    > > differently. Most likely, APIPA is turned off on Client01. Client02 is
    > > working as expected.

    >
    > Collect me if I'm long, but it seems the bottom line is that Clinet02
    > cannot see the network (or at least the DHCP Server).
    >
    > kpg
    >


    It appears that client02 is working right. If there is no DHCP server
    wehn it reboots, it should get an APIPA address (unless APIPA has been
    disabled or an alternate IP has been configured.)
     
    Ben Smith, Nov 21, 2005
    #7
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