Microsoft KB Archive/190552

= Windows NT 4.0 DHCP Client Modified to be RFC 2131 Retransmission Compliant =

Article ID: 190552

Article Last Modified on 11/1/2006

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APPLIES TO


 * Microsoft Windows NT Server 4.0, Terminal Server Edition
 * Microsoft Windows NT Workstation 4.0 Developer Edition
 * Microsoft Windows NT Server 4.0 Standard Edition
 * Microsoft Windows NT Server 4.0 Enterprise Edition

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This article was previously published under Q190552





SYMPTOMS
There will be occasional failures to lease an IP address during busy network or DHCP server times.



CAUSE
The DHCP client retry mechanism has been modified to be in compliance with RFC 2131.

The mechanism is described in RFC 2131, which states:

DHCP clients are responsible for all message retransmission. The client MUST adopt a retransmission strategy that incorporates a randomized exponential backoff algorithm to determine the delay between retransmissions. The delay between retransmissions SHOULD be chosen to allow sufficient time for replies from the server to be delivered based on the characteristics of the internetwork between the client and the server. For example, in a 10Mb/sec Ethernet internetwork, the delay before the first retransmission SHOULD be 4 seconds randomized by the value of a uniform random number chosen from the range -1 to +1. Clients with clocks that provide resolution granularity of less than one second may choose a non-integer randomization value. The delay before the next retransmission SHOULD be 8 seconds randomized by the value of a uniform number chosen from the range -1 to +1. The retransmission delay SHOULD be doubled with subsequent retransmissions up to a maximum of 64 seconds. The client MAY provide an indication of retransmission attempts to the user as an indication of the progress of the configuration process.

The new Windows NT DHCP client (Dhcpcsvc.dll) behaves as described in the RFC. It sends the first DHCP request plus up to three retries, if needed.



RESOLUTION
To resolve this problem, obtain the latest service pack for Windows NT 4.0 or Windows NT Server 4.0, Terminal Server Edition. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

152734 How to Obtain the Latest Windows NT 4.0 Service Pack



STATUS
Microsoft has confirmed that this is a problem in Windows NT 4.0 and Windows NT Server 4.0, Terminal Server Edition. This problem was first corrected in Windows NT 4.0 Service Pack 4.0 and Windows NT Server 4.0, Terminal Server Edition Service Pack 4.

Keywords: kbhotfixserver kbqfe kbbug kbfix kbqfe KB190552

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