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Windows XPdoes not keep its DHCP IP address if a DHCP server is not available

Posted on 2010-09-07
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Last Modified: 2012-05-10
Hi,

i have many client computer does not keep its DHCP IP address if a DHCP server is not available.

My client is Windows XP SP2/SP3 and my DHCP server is WIndows 2008 SP1.

Thanks for your help
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Question by:cawasaki
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by:Bidonet
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Normally, when the DHCP is not availble you won't get an IP address.  If the DHCP server becomes unavailable after the client got the IP address, it should work until the lease time expires.  Then, the client must contact the DHCP to renew the address, otherwise, no IP address.

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by:sentner
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If you're saying it loses the address as soon as the DHCP serve becomes unavailable, it may be that your router is setting the DHCP leases to expire quickly.  

On your computer, check the lease expiration time.  

ipconfig /all

Note also though that if your computer is rebooted or disconnected and reconnected to the network, it will drop the lease anyways, and will not revert to the old DHCP supplied address, as it needs to get a new one.  
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Alan Gunn earned 500 total points
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Additonally, if your machine has a live network cable connected but no DHCP server, the machine will assign itself a 169.254.*.* address.
From
http://www.computing.net/answers/networking/i-have-a-169254xx-ip-address-c/22962.html

" If your local IP address is returned as 169.254.y.z with a subnet mask of 255.255.0.0, the IP address was assigned by the Automatic Private IP Addressing (APIPA) feature of Windows XP Professional. This assignment means that TCP/IP is configured for automatic configuration, that no DHCP server was found, and that no alternative configuration is specified. This configuration has no default gateway for the interface. "
This can be a problem because the machine will stop looking for a DHCP server and have to be re-started (Or, if the user has rights,  Ipconfig /release , Ipconfig /renew can be run at a command prompt).
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by:Krzysztof Pytko
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Yup, sentner is right. DHCP client need to renew its DHCP lease, so contact with DHCP server is required. If it is not available then no IP address is issued. Then you see 169.254.x.y/16, it is called APIPA (Automatic Private IP Addressing) If you see this IP address you know that client could not locate or connect to DHCP server.

In your case you should:

- check how long time have your leases in DHCP scope's properites you can check it and adjust

- investigate why your DHCP server is so often offline.

You can read in this article how the renwal proces looks like

http://technet.microsoft.com/en-us/library/cc958919.aspx

and here overview of whole lease renew
http://technet.microsoft.com/en-us/library/cc958935.aspx
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