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Windows 2003 DHCP Server Advanced Configuration - Part 2

Posted in Windows 2003 Server

Part 1 of our Windows 2003 DHCP Server Advanced Configuration article explained the creation and configuration of DHCP Scope options and how to configure various DHCP server settings. This article focuses on backing up and restoring the DHCP server database, troubleshooting DHCP using a packet analyser and more.

Backing up the DHCP database

Our DHCP server is fully functional but it may not always remain that way. We definitely want to back it up so we can quickly restore the functionality in the event of a disaster.

The DHCP scopes, settings and configuration are actually kept in a database file, and the database is automatically backed up every 60 minutes. But to manually back it up:

  • On the DHCP MMC, right-click the server node and choose Backup
  • When the Browse for Folder window comes up, verify that it points to C :\windows\system32\dhcp\backup and click OK:

tk-windows-dhcp-2k3-advanced-12

Restoring the DHCP Database

Let us imagine that a disaster with the DHCP server did occur and that we now have to restore the DHCP functionality. Restoring the DHCP database is just as simple as backing it up:

  1. 1. On the DHCP MMC, right-click the server node and choose Restore
  2. 2. When the Browse for Folder window comes up, click OK
  3. 3. You will receive a prompt informing you that the DHCP service will need to be stopped and restarted for the restore to take place. Click OK

The DHCP database will then be restored.

Troubleshooting DHCP

Windows 2003 DHCP Server Advanced Configuration - Part 1

Posted in Windows 2003 Server

In this article, we will cover more advanced DHCP features and topics such as server options, superscopes, multicast scopes, dynamic DNS, DHCP database backup and restoration, DHCP migration, and DHCP troubleshooting. We will cover these topics in two ways: by building out from our earlier implementation and by using our imagination!

Ok, using our imagination for this purpose may seem silly but doing so will give us the opportunity to indirectly learn how, why, and where these advanced DHCP features and topics come into play in a real-world network and how other networking technologies are involved in a DHCP implementation.

We will imagine that we are building our DHCP server for a company that has two buildings, Building A and Building B, each with a single floor (for now). Building A is on a 192.168.0.0/24 network and Building B is on a 192.168.1.0/24 network.

Although each building has its own DNS server (192.168.0.252 and 192.168.1.252), WINS server (192.168.0.251 and 192.168.1.251) and Cisco Catalyst 4507R-E switch (192.168.0.254 and 192.168.1.254), only a single DHCP server exists – it is the one that we have been building and it resides in Building A.

The clients and servers in each building connect to their respective Cisco Catalyst switches and the switches are uplinked to a Cisco router for Internet connectivity. The only notable configuration is with the Building B switch: It is configured with the ip helper-address 192.168.0.253 command.

The ip helper-address command tells the switch to forward DHCP requests in the local subnet to the DHCP server, since the clients in Building B cannot initially communicate with the DHCP server directly. We are not concerned with any other configuration or networking technologies for now.

Server Options

The specifications of our imaginary company state that the company has two buildings – Building A and Building B. In our first article, we created a scope called “Building A, Floor 1” so a scope for our first building is already made. In this article, we will create a scope for Building B, Floor 1, using the instructions from our Basic DHCP Configuration article and the following specifications for the scope:

tk-windows-dhcp-2k3-advanced-1

After creating the scope, we want to activate it as well.

Notice that, in creating this scope, we had to input a lot of the same information from our “Building A, Floor 1” scope. In the event that we had several other scopes to create, we would surely not want to be inputting the same information each time for each scope.

That is where server options are useful. Server options allow you to specify options that all the scopes have in common. In creating two scopes, we noticed that our scopes had the following in common:

  • DNS servers
  • WINS servers
  • Domain name

To avoid having to enter this information again, we will create these options as server options. To do this:

1. On the DHCP MMC, right-click Server Options and choose Configure Options

tk-windows-dhcp-2k3-advanced-2

Windows 2003 DHCP Server Installation & Configuration

Posted in Windows 2003 Server

DHCP (Dynamic Host Configuration Protocol) is a protocol that allows clients on a network to request network configuration settings from a server running the DHCP server service which, in our case, will be Windows Server 2003. Additionally the protocol allows the clients to self-configure those network configuration settings without the intervention of an administrator. Some of the settings that a DHCP server can provide to its clients include the IP addresses for the DNS servers, the IP addresses for the WINS servers, the IP address for the default gateway (usually a router) and, of course, an IP address for the client itself.

This article will discuss and walk you through the steps of installing and configuring DHCP on a Windows Server 2003 member server, specifically focusing on setting up a scope and its accompanying settings. The same configuration can be applied to a standalone server even though the step-by-step details differ slightly. The upcoming 'Advanced DHCP Server Configuration on Windows 2003' article will discuss other DHCP options and features such as superscopes, multicast scopes, dynamic DNS, DHCP Backup and more.

While our articles make use of specific IP addresses and network settings, you can change these settings as needed to make them compatible with your LAN – This won't require you to make changes to your LAN, but you'll need to have a slightly stronger understanding of DHCP and TCP/IP.

Assigning the Server a Static IP Address

Before we install the DHCP server service on Windows Server 2003, we need to assign the Windows server a static IP address. To do this:

1. Go to Start > Control Panel > Network Connections , right-click Local Area Connection and choose Properties .

2.  When the Local Area Connection Properties window comes up, select Internet Protocol (TCP/IP) and click the Properties button.

3.  When the Internet Protocol (TCP/IP) window comes up, enter an IP address , subnet mask and default gateway IP address that is compatible with your LAN.

We've configured our settings according to our network, as shown below:

tk-windows-dhcp-2k3-basic-1

4. Enter 192.168.0.252 for the Preferred DNS server and 192.168.1.252 for the Alternate DNS server. The Preferred and Alternate DNS server IP addresses are optional for the functionality of the DHCP server, but we will populate them since you typically would in a real-world network. Usually these fields are populated with the IP addresses of your Active Directory domain controllers.

5. After filling out those fields, click OK and OK to save and close all windows.

Install DHCP Server Service on Windows Server 2003

Our server now has a static IP address and we are now ready to install the DHCP server service. To do this:

1. Go to Start > Control Panel > Add or Remove Programs .

2. When the Add or Remove Programs window launches, click Add/Remove Windows Components in the left pane.

3. When the Windows Components Wizard comes up, scroll down and highlight Networking Services and then click the Details button.

tk-windows-dhcp-2k3-basic-2

Renaming Windows 2000 Domain Name

Posted in Windows 2000 Server

Sometimes renaming a domain is an essential business requirement. There are many situations, such as mergers, change of company name or migration from a test environment to a production environment, that require you to change the existing domain name.

However, changing a domain name in Windows Server 2000 is not a simple or straightforward process. It is a time consuming and complex procedure, which requires extensive work.

The renaming of a Windows 2000 domain may impact other server applications that are running in the domain, such as Exchange Server and other custom applications that are closely integrated with Active Directory and use hard coded NETBIOS names.

The major task in renaming a domain is to revert the Windows Server 2000 to Windows NT and then upgrade it to Windows Server 2000 with a new DNS (FQDN) name. If there is more than one domain controller in the domain then all the Windows 2000 domain controllers must be demoted to member servers before renaming the desired domain controller.

Active Directory Tombstone Lifetime Modification

Posted in Windows 2003 Server

Introduction

Tombstone is a container object that contains the deleted objects from Active Directory. Actually when an object is deleted from Active Directory, it is not physically removed from the Active Directory for some days. Rather, the Active Directory sets the ‘isDeleted' attribute of the deleted object to TRUE and move it to a special container called Tombstone, previously known as CN=Deleted Objects.

The tombstones cannot be accessed through Windows Directories or through Microsoft Management Console (MMC) snap-ins. However, tombstones are available to Directory Replication Process, so that the tombstones are replicated to all the domain controllers in the domain. This process ensures that the object deleted is deleted from all the computers throughout the Active Directory.

The tombstone lifetime attribute is the attribute that contains a time period after which the object is physically deleted from the Active Directory. The default value for the tombstone lifetime attribute is 60 days. However, you can change this value if required. Usually tombstone lifetime value is kept longer than the expected replication latency between the domain controllers so that the tombstone is not deleted before the objects are replicated across the forest.


The tombstone lifetime attribute remains same on all the domain controllers and it is deleted from all the servers at the same time. This is because the expiration of a tombstone lifetime is based on the time when an object was deleted logically from the Active Directory, rather than the time when it is received as a tombstone on a server through replication.

Changing Tombstone Lifetime Attribute

The tombstone lifetime attribute can be modified in three ways: Using ADSIEdit tool, using LDIF file, and through VBScript.

Using ADSIEdit Tool

The easiest method to modify tombstone lifetime in Active Directory is by using ADSIEdit. The ADSIEdit tool is not installed automatically when you install Windows Server 2003. You need to install it separately by installing support tools from Windows Server 2003 CD.
If you haven't got your CD's in hand, you can simply download the Windows 2003 SP1 Support Tools from Firewall.cx here.
To install ADSIEdit tool and to modify tombstone lifetime in Active Directory using this tool, you need to:

  1. Insert the Windows Server 2003 CD.
  2. Browse the CD to locate the Support\Tools directory.
  3. Double-click the suptools.msi to proceed with the installation of support tools.
  4. Select Run command from the Start menu.
  5. Type ADSIEdit.msc to open the ADSI Editor, as shown below:

tk-windows-tombstone-1

The ADSI Edit window appears:
tk-windows-tombstone-2

6. Expand Configuration node then subsequently expand CN=Configuration, DC Firewall, DC=cx node.
7. Expand CN-Services node.
8. Drill down to CN=Directory Service under CN Windows NT , as shown in the figure below:

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