Clients Do Not Update DHCP Scope Options on Lease Renewal

Symptoms

When your Windows-based Dynamic Host Configuration Protocol (DHCP) client computer renews the lease on an Internet Protocol (IP) address, your computer may not update changes to DHCP scope options.

Resolution

To work around this problem, release your IP address and start a new lease. Note that you may need to restart your computer after you release your IP address.

Status

Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.

More Information

The following example demonstrates how the Windows 98 IP stack does not accept DHCP scope option updates through the normal renewal process like Microsoft Windows NT does. Most of the scope options that can be altered or changed are not reflected on a Windows 98 client computer unless the client lease is released and then renewed. It is normally expected that DHCP scope option updates are received and processed during the renewal phase without having to release the client IP address. When clients are shut down, they do not release their IP addresses. This means a Windows 98-based computer could be restarted many times or left on for many days, and as long as it was only renewing the existing lease (not obtaining a new one), the new DHCP options would never be updated without "manually" releasing the IP lease from the client. This can be administratively challenging in many environments.

To set up this example:

Set up a DHCP server with a scope (no options) with a lease time of 10 minutes. Start the Windows-based client computer. This client should obtain an IP address from the DHCP server.

Add the following scope options to the DHCP server:


router (3)
dns server (6)
domain name (15)
wins server (44)
node type (46)<BR/>
netbios scope id (47)
When the Windows-based client computer renews the lease, it displays the following new options:


dns server (6)
domain name (15)
No other options will appear or be used by Windows. The next step is to perform a release/renew in an attempt to get additional options. When you do the release/renew, the following options will appear:


router (3)
dns server (6)
domain name (15)
wins server (44)
node type (46)
The only way to get the NETBIOS scope ID to take effect is to restart your computer. This problem is documented for Windows 95 in the following article in the Microsoft Knowledge Base:

145980 Node Type And Scope ID Not Updated Upon Lease Renewal
This article also states that the node type does not change until you restart your computer, but in Windows it appears to only take a release action or renew action to accept the information. To change it after this first initialization however, you must restart your computer.

Once this information has been accepted by the Windows client computer, you can test how well Windows removes options when they have been removed from the DHCP server scope.

Changing the DNS server option takes effect on a renewal, changing domain name, WINS server, or router options require a release or renew action, and changing the node type or scope ID requires you restart your computer.

NOTE: The NetBios Scope Id is a legacy option. The references to the NetBios Scope ID above are mentioned in this article for completeness only. If you are not using Scope IDs you do not need this option.
Propriétés

ID d'article : 224175 - Dernière mise à jour : 26 févr. 2007 - Révision : 1

Commentaires