NetShell Utility Truncates Long MAC Address Entries When Dumping DHCP Database (318934)

SYMPTOMS

When you use the NetShell utility (Netsh.exe) to display the Dynamic Host Configuration Protocol (DHCP) server configuration, DHCP reservation information may be truncated when displayed.

NOTE: To display the DHCP server configuration by using Netsh.exe, type the following at a command prompt, and then press ENTER:

netsh dhcp dump

CAUSE

This behavior may occur if both of the following conditions are true:

The DHCP server contains a DHCP reservation that uses a unique ASCII identifier (such as a Domain Name Service [DNS] name) instead of a media access control (MAC) address with which to identify the reserved computer.

-and-
That ASCII identifier is more than 30 characters in length.

The Windows variable, in which the client identifier is stored, is undersized. The current size for the client identifier is 40 bytes. However, it should be 255 bytes.

RESOLUTION

To resolve this problem, obtain the latest service pack for Windows 2000. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

260910 How to Obtain the Latest Windows 2000 Service Pack

The English-language version of this fix has the file attributes (or later) that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To calculate the difference between UTC and local time, click the Time Zone tab in the Date and Time tool in Control Panel.

   Date         Time   Version        Size     File name
   -------------------------------------------------------
   06-Mar-2002  21:55  5.0.2195.5035  306,448  Dhcpmon.dll

STATUS

Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article. This problem was first corrected in Windows 2000 Service Pack 3.

MORE INFORMATION

Requests for Comment (RFC) 2131 and 2132 specify that a specific DHCP client can be identified by a unique identifier other than a MAC address -- for example, a DNS name. This feature minimizes the overloading of the chaddr field in BOOTP messages, where chaddr is used both as the hardware address for the BOOTP reply message transmission and as the client identifier.

The client identifier may contain a hardware address (MAC address) that is exactly the same as the contents of the chaddr field, or it may contain another type of identifier, such as a DNS name. The client identifier must be unique to that client in the subnet to which the client is attached.