Q190552: WinNT 4.0 DHCP Client Modified to meet RFC 2131

Article: Q190552
Product(s): Microsoft Windows NT
Version(s): WinNT:4.0
Operating System(s): 
Keyword(s): kbWinNT400sp4fix
Last Modified: 09-AUG-2001

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The information in this article applies to:

- Microsoft Windows NT Workstation version 4.0 
- Microsoft Windows NT Server version 4.0 
- Microsoft Windows NT Server, Enterprise Edition version 4.0 
- Microsoft Windows NT Server version 4.0, Terminal Server Edition 
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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,
please see the following article in the Microsoft Knowledge Base:

  Q152734 How to Obtain the Latest Windows NT 4.0 Service Pack


STATUS
======

Microsoft has confirmed this to be 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.

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Keywords          : kbWinNT400sp4fix 
Technology        : kbWinNTsearch kbWinNTWsearch kbWinNTW400 kbWinNTW400search kbWinNT400search kbWinNTSsearch kbWinNTSEntSearch kbWinNTSEnt400 kbWinNTS400search kbWinNTS400 kbNTTermServ400 kbNTTermServSearch
Version           : WinNT:4.0
Hardware          : ALPHA x86
Issue type        : kbbug
Solution Type     : kbfix

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