DHCP Step-by-Step Guide: Demonstrate DHCP Failover – Clustering in a Test Lab
A cluster is a group of independent computers that work together to increase the availability of applications and services. Physical cables and software connect the clustered servers (called nodes) so that if one fails another can take its place. In the case of this lab, the dual-clustered servers will provide uninterrupted DHCP services even if one of the clustered nodes fails. This guide describes clustering technologies that can be used with DHCP for high availability or failover deployments.
Quorum-based failover clustering
Quorum refers to the number of available cluster nodes that the clustering configuration needs to continue to function. Each cluster has a specific set of nodes and a specific quorum configuration. Cluster nodes cast votes, and clusters keep track of how many votes make up a majority (quorum). If the number drops below the majority, the cluster stops functioning.
If the network fails, the cluster service uses a voting algorithm to determine which cluster has the quorum of votes (in some cases, disks and file shares count in the quorum vote as well). Nodes still listen for the presence of other nodes in case one appears again on the network, but the nodes do not begin to function as a cluster until the quorum exists again.
There are four quorum modes:
Node Majority:Each node that is available and in communication can vote. The cluster functions only with a majority of the votes—that is, more than half. Node majority is not recommended with an even number of nodes; in this case, consider any of the other three quorum modes.
Node and Disk Majority: Each node plus a designated disk in the cluster storage (the disk witness) can vote whenever they are available and in communication. The cluster functions only with a majority of the votes—that is, more than half.
Node and File Share Majority: Each node plus a designated file share (the file share witness) can vote whenever they are available and in communication. The cluster functions only with a majority of the votes—that is, more than half.
No Majority: Disk Only: The cluster has quorum if one node is available and in communication with a specific disk in the cluster storage. Only the nodes that are also in communication with that disk can join the cluster.
A five-node cluster using Node Majority stops functioning as a cluster when communication to the majority of cluster nodes is lost.
So, for example, nodes 1, 2, and 3 remain a cluster even if they lose communication with nodes 4 and 5. Nodes 1, 2, and 3 make up a majority of the nodes and so the cluster continues to function. When nodes 4 and 5 regain communication, they return to the cluster. On the other hand, if nodes 3, 4, and 5 lose communication with the cluster, the cluster no longer functions because the nodes still in communication no longer make up the majority of the cluster. All five nodes will wait for a majority of nodes (in this case, three or more) to regain communication before reforming the cluster.
There are recommended quorum modes that are based on the number of nodes in a cluster. This lab shows how to set up a DHCP cluster using the Node and File Share Majority quorum mode.
In this guide
This guide provides an introduction to quorum-based clustering and instructions for setting up a test lab using two Windows DHCP servers, one Windows Storage Server, and two Windows DHCP clients.
Important
The following instructions describe how to configure a test lab using the minimum number of computers. Individual computers are needed to separate the services provided on the network and to clearly show the desired functionality. This configuration is neither designed to reflect best practices nor does it reflect a desired or recommended configuration for a production network. The configuration, including IP addresses and all other configuration parameters, is designed only to work on a separate test lab network.
Scenario overview
In this test lab, quorum-based failover clustering is deployed using two computers running Windows Server® 2008 R2 that have the DHCP Server service installed and two client computers running Windows Server® 2008 R2 with the DHCP Client service running. A computer running Windows Storage Server® 2003 Enterprise Edition R2 is also used in the test lab as a domain controller, DNS server, and storage server.
Software requirements
The following are required components of the test lab:
The product disc for Windows Server® 2008 R2.
The product disc for Windows Storage Server®.
The product disc for Windows® 7.
Hardware requirements
The following are required components of the test lab:
Network adapters and cable (for network communication): The network hardware, like other components in the failover cluster solution, must be compatible with Windows Server 2008 R2. Your network adapters must be dedicated to either network communication or iSCSI, but not both.
In the network infrastructure that connects your cluster nodes, avoid having single points of failure. There are multiple ways to accomplish this. You can connect your cluster nodes by multiple, distinct networks. Alternatively, you can connect your cluster nodes with one network that is constructed with redundant switches, redundant routers, or similar hardware that removes single points of failure.
Note
If you connect cluster nodes with a single network, the network will pass the redundancy requirement in the Validate a Configuration Wizard later in this test lab. However, the report from the wizard will include a warning that the network should not have single points of failure.
Device controllers or appropriate adapters for iSCSI storage:
- For Serial Attached SCSI or Fibre Channel: If you are using Serial Attached SCSI or Fibre Channel, the mass-storage device controllers that are dedicated to the cluster storage should be identical in all clustered servers. They should also use the same firmware version.
Note
With Windows Server 2008 R2, you cannot use parallel SCSI to connect the storage to the clustered servers.
- **For iSCSI**: If you are using iSCSI, each clustered server must have one or more network adapters or host bus adapters that are dedicated to cluster storage. The network you use for iSCSI cannot be used for network communication. In all clustered servers, the network adapters you use to connect to the iSCSI storage target should be identical, and we recommend that you use Gigabit Ethernet or higher.
Note
You cannot use teamed network adapters because they are not supported with iSCSI.
- Storage: You must use shared storage that is compatible with Windows Server 2008 R2.For a two-node failover cluster, such as the cluster in this test lab, the storage should contain at least two separate volumes , configured at the hardware level. Do not expose the clustered volumes to servers that are not in the cluster. One volume will function as the witness disk. One volume will contain the files that are being shared between the cluster nodes. This volume serves as the shared storage on which you will create the virtual machine and the virtual hard disk. To complete the steps as described in this document, you only need to expose one volume.
Note
If you plan to create and test more than one virtual machine, as a best practice, consider creating a separate volume for each virtual machine.
Storage requirements include the following:
- To use the native disk support included in failover clustering, use basic disks, not dynamic disks.
- For the partition style of the disk, you can use either master boot record (MBR) or GUID partition table (GPT).
The witness disk is a disk in the cluster storage that is designated to hold a copy of the cluster configuration database. (A witness disk is part of some, but not all, quorum configurations.) For this two-node cluster, the quorum configuration will be Node and File Share Majority. Node and File share Majority means that the nodes and the witness file share each contain copies of the cluster configuration, and the cluster has quorum as long as a majority (two out of three) of these copies are available.
Deploying storage area networks with failover clusters
When deploying a storage area network (SAN) with a failover cluster, follow these guidelines:
- Confirm compatibility of the storage: Confirm with manufacturers and vendors that the storage—including drivers, firmware, and software used for the storage—are compatible with failover clusters in Windows Server 2008 R2.
Important
Storage that was compatible with server clusters in Windows Server® 2003 Enterprise Edition may not be compatible with failover clusters in Windows Server 2008 R2. Contact your vendor to ensure that your storage is compatible with failover clusters in Windows Server 2008 R2.
Windows Server 2008 R2 failover clusters include the following new requirements for storage:
- Because of improvements in failover, clusters require that the storage respond correctly to specific SCSI commands. The storage must follow the SCSI Primary Commands-3 (SPC-3) standard. In particular, the storage must support Persistent Reservations as specified in the SPC-3 standard.
- The miniport driver used for the storage must work with the Microsoft Storport storage driver.
Isolate storage devices, one cluster per device: Servers from different clusters must not be able to access the same storage devices. In most cases, a LUN that is used for one set of cluster servers should be isolated from all other servers through LUN masking or zoning.
Consider using multipath I/O software: In a highly available storage fabric, you can deploy failover clusters with multiple host bus adapters by using multipath I/O (MPIO) software. This provides the highest level of redundancy and availability. For Windows Server 2008 R2, your multipath solution must be based on Microsoft MPIO. Your hardware vendor will usually supply an MPIO device-specific module (DSM) for your hardware, although host bus adapters and MPIO software can be very version sensitive. If you are implementing a multipath solution for your cluster, you should work closely with your hardware vendor to choose the correct adapters, firmware, and software for Windows Server 2008 R2.
Network infrastructure and domain account requirements for a two-node failover cluster
You will need the following network infrastructure for a two-node failover cluster and an administrative account with the following domain permissions:
Network settings and IP addresses: When you use identical network adapters for a network, also use identical communication settings on those adapters (for example, speed, duplex mode, flow control, and media type). Also, compare the settings between the network adapter and the switch it connects to and make sure that no settings are in conflict.
If you have private networks that are not routed to the rest of your network infrastructure, ensure that each of these private networks uses a unique subnet. This is necessary even if you give each network adapter a unique IP address. For example, if you have a cluster node in a central office that uses one physical network, and another node in a branch office that uses a separate physical network, do not specify 10.0.0.0/24 for both networks, even if you give each adapter a unique IP address.
DNS: The servers in the cluster must be using Domain Name System (DNS) for name resolution. The DNS dynamic update protocol can be used.
Domain role: All servers in the cluster must be in the same Active Directory domain. As a best practice, all clustered servers should have the same domain role (either member server or domain controller). The recommended role is member server.
Domain controller: We recommend that your clustered servers be member servers of an Active Directory domain. If they are, you need an additional server that acts as the domain controller in the domain that contains your failover cluster.
Clients: As needed for testing, you can connect one or more networked clients to the failover cluster that you create, and observe the effect on a client when you move or fail-over the highly available virtual machine from one cluster node to the other.
Account for administering the cluster: When you first create a cluster or add servers to it, you must be logged on to the domain with an account that has local administrator rights on all servers in that cluster. The account does not need to be a Domain Administrator account, but can be a Domain Users account that is in the DHCP Administrators group on each clustered server. In addition, if the account is not a Domain Administrator account, the account (or the group that the account is a member of) must be given the Create Computer Objects and Read All Properties permissions in the domain.
Steps for configuring the test lab
Following are the installation and configuration, and post-installation configuration stages required to set up this test lab:
Configure Storage Server 1 (SS1).
SS1 is a server computer running Windows Storage Server® 2003 Enterprise Edition SP2. SS1 is configured as a storage server for clustering setup, and as the Active Directory domain controller and DNS server for the test lab domain.
Configure DHCP Server 1.
DHCP Server 1 is a server computer running Windows Server 2008 R2. DHCP Server 1 is configured with the DHCP Server service and functions as a DHCP server in the domain. DHCP Server 1 is configured as one of the cluster nodes for failover of the DHCP service.
Configure DHCP Server 2.
DHCP Server 2 is a server computer running Windows Server 2008 R2. DHCP Server 2 is configured with the DHCP Server service and functions as a DHCP server in the domain. DHCP Server 2 is configured as the other cluster node for failover of the DHCP service.
Configure DHCP Client 1
DHCP Client 1 is a computer running Windows 7 that is configured to request IP addresses from the DHCP server.
After you configure all the computers and features, this guide provides steps to demonstrate how clustering provides uninterrupted DHCP service when DHCP Server 1 becomes unavailable.
Configure SS1
SS1 is a computer running Windows Storage Server 2003® Enterprise Edition SP2, which provides the following services:
A domain controller for the contoso.com Active Directory domain.
A DNS server for the contoso.com DNS domain.
A storage server for the DHCP cluster.
SS1 configuration consists of the following steps:
Install the operating system.
Configure TCP/IP.
Install Active Directory and DNS.
Create a user account and group in Active Directory.
The following sections explain these steps in detail.
Install the operating system on SS1
Install Windows Storage Server 2003® Enterprise Edition SP2 as a stand-alone server.
To install the operating system on DC1
Start your computer using the Windows Storage Server 2003® Enterprise Edition product disc.
When prompted for a computer name, type SS1.
Configure TCP/IP on SS1
Configure the TCP/IP protocol with a static IP address of 172.16.1.1 and the subnet mask of 255.255.255.0.
To configure TCP/IP on SS1
Click Start, click Control Panel, and then double-click Network Connections.
Right-click Local Area Connection, and then click Properties.
Click Internet Protocol (TCP/IP), and then click Properties.
Select Use the following IP address. Type 172.16.1.1 next to IP address and 255.255.255.0 next to Subnet mask.
Verify that Preferred DNS server is blank.
Click OK, click Close, and then close the Network Connections window.
Configure SS1 as a domain controller and DNS server
SS1 will serve as the only domain controller and DNS server for the contoso.com domain.
To configure SS1 as a domain controller and DNS server
To start the Active Directory Installation Wizard, click Start, click Run, type dcpromo, and then press ENTER.
In the Active Directory Installation Wizard dialog box, click Next.
Operating system compatibility information is displayed. Click Next again.
Verify that Domain controller for a new domain is selected, and then click Next.
Verify that Domain in a new forest is selected, and then click Next twice.
On the Install or Configure DNS page, select No, just install and configure DNS on this computer, and then click Next.
Type contoso.com next to Full DNS name for new domain, and then click Next.
Confirm that the Domain NetBIOS name shown is CONTOSO, and then click Next.
Accept the default Database Folder and Log Folder directories, and then click Next.
Accept the default folder location for Shared System Volume, and then click Next.
Verify that Permissions compatible only with Windows 2000 or Windows Server 2003 operating systems is selected, and then click Next.
Leave the Restore Mode Password and Confirm Password text boxes blank, and then click Next.
View the summary information provided, and then click Next.
Wait while the wizard completes configuration of Active Directory and DNS services, and then click Finish.
When prompted to restart the computer, click Restart Now.
After the computer restarts, log in to the CONTOSO domain using the Administrator account.
Create a user account in Active Directory
Next, create a user account in Active Directory. You will use this account when logging in to DHCP Server 1 and DHCP Server 2.
To create a user account in Active Directory
Click Start, point to Administrative Tools, and then click Active Directory Users and Computers.
In the console tree, double-click Contoso.com, right-click Users, point to New, and then click User.
In the New Object - User dialog box, next to Full name, type User1, and in User logon name, type User1.
Click Next.
In Password, type the password that you want to use for this account, and in Confirm password, type the password again.
Clear the User must change password at next logon check box, and select the Password never expires check box.
Click Next, and then click Finish.
Leave the Active Directory Users and Computers console open for the following procedure.
Add user1 to the DHCP Administrators group
Next, add the newly created user to the DHCP Administrators group and use it for all of the configuration activities.
To add a user to the DHCP Administrators group
In the Active Directory Users and Computers console tree, click Users.
In the details pane, double-click DHCP Administrators.
In the DHCP Administrators Properties dialog box, click the Members tab, and then click Add.
Under Enter the object names to select (examples), type User1, the user name that you created in the preceding procedure, and then click OK twice.
Leave the Active Directory Users and Computers console open for the following procedure.
Configure iSCSI target on SS1
iSCSI is a storage area network (SAN) protocol that allows iSCSI clients (called initiatiors) to send SCSI commands to iSCSI storage devices (called targets) on remote computers. Unlike Fibre Channel, iSCSI can run over existing IP network infrastructure, thereby requiring no special cabling and providing a low cost alternative to Fibre Channel. The iSCSI clients connect and access the iSCSI target using an identifier based on IP address.
To configure iSCSI on Storage Server 1
Click Start, point to Administrative Tools and then click Microsoft iSCSI Software Target.
Right-click iSCSI Target and then click Create iSCSI Target.
Follow the Wizard directions to create a new iSCSI target.
Note
After naming the iSCSI target, the next step is to configure an identifier for the iSCSI initiators that connect to the iSCSI target. The iSCSI target uses the identifier, referred to as an iSCSI Qualified Name (IQN), to identify the iSCSI initiator when it logs into the iSCSI target. Click Advanced and add the IP address of the Windows Storage Server (SS1) to the list of iSCSI initiators for this iSCSI target.
Provision a virtual disk for the iSCSI target
After creating an iSCSI target and IQN, the next step is to provision storage for the iSCSI target. The procedure involves the following steps:
Create a virtual disk for the iSCSI target.
Add iSCSI initiators to the iSCSI target.
Mount the virtual disk and initialize it.
Partition and format the virtual disk.
Unmount the disk.
To provision a virtual disk for the iSCSI target
In the iSCSI Target console, click contoso.com under iSCSI Targets and then click Create Virtual Disk for iSCSI Target.
Follow the Wizard directions to create a virtual disk.
After you complete the wizard, configure the clients for the iSCSI target by adding the IP addresses of the node (SS1) and cluster servers (DHCP Server 1 and 2).
In the iSCSI Target console, right-click contoso.com and then click Properties.
Click iSCSI Initiators, click Add, type 172.16.1.1, and then click OK. Repeat to add 172.16.1.2 and 172.16.1.3, and then click OK.
Next, create a partition on the virtual disk. For this, the virtual disk needs to be mounted like any other storage device. This can be done by right clicking the virtual disk in the iSCSI Target console.
In the Microsoft iScsi Software Target tree, right-click Virtual Disk 0, point to Disk Access and then click Mount Read/Write.
Click Yes when prompted about data corruption, and then click OK.
Next, the virtual disk needs to be initialized and partitioned using the Disk Management console (diskmgmt.msc), which starts the Disk Initialization and Conversion Wizard. The initialization creates a master boot record (MBR) on the disk.
Note
The wizard also enables you to convert the disk to a dynamic disk. Dynamic disks provide features such as the ability to create volumes that span multiple disks (spanned and striped volumes), and the ability to create fault tolerant volumes (mirrored and RAID-5 volumes). For the purpose of this test lab you will not create a dynamic disk because a basic disk is all that is required.
Click Start, type diskmgmt.msc and then press ENTER.
Follow the wizard directions to initialize the disk.
After initialization, you need to partition and format the virtual disk before you configure access to the iSCSI initiators.
In the Disk Management Console, right-click the Unallocated space and then click New Partition.
Follow the wizard directions to partition the disk.
After you partition and format the virtual disk, you need to dismount it using the iSCSI Target console.
In the Microsoft iSCSI Software Target tree, click Devices, right-click Virtual Disk 0, point to Disk Access, and then click Dismount.
Click Yes when warned about dismounting a virtual disk, and then click OK.
Configure DHCP Servers 1 and 2
For purposes of this test lab, DHCP Server 1 and DHCP Server 2 run Windows Server 2008 R2 and host the DHCP service as primary server and secondary server respectively for failover cluster configuration, which provides IP addresses and leases for the requesting DHCP clients. DHCP Server 1 and DHCP Server 2 configuration consists of the following steps:
Complete the following procedure on both DHCP Server 1 and DHCP Server 2.
Install the operating system.
Configure TCP/IP.
Join the computer to the domain.
Install DHCP server roles.
Configure DHCP.
Install Windows Server 2008 R2
To install Windows Server
Start your computer using the Windows Server 2008 R2product CD.
When prompted for the installation type, choose Custom.
Follow the instructions that appear on your screen to finish the installation.
Next, install the DHCP Server role on DHCP Server 1 and DHCP Server 2.
Install the DHCP server role
Click Start, and then click Server Manager.
Under Roles Summary, click Add roles, and then click Next.
On the Select Server Roles page, select the DHCP server, and then click Next twice.
On the Select Network Connection Bindings page, verify that 172.16.1.2 is selected, and then click Next on DHCP Server 1. Similarly, on the Select Network Connection Bindings page, verify that 172.16.1.3 is selected, and then click Next on DHCP Server 2.
On the Specify IPv4 DNS Server Settings page, verify that contoso.com is listed under Parent domain.
Type 172.16.1.1 under Preferred DNS server IP address, and click Validate. Verify that the result returned is valid, and then click Next.
On the Specify WINS Server Settings page, accept the default setting of WINS is not required on this network, and then click Next.
On the Add or Edit DHCP Scopes page, click Add.
In the Add Scope dialog box, type SS Scope next to Scope Name. Next to Starting IP Address, type 172.16.1.4, next to Ending IP Address, type 172.16.1.204, and next to Subnet Mask, type 255.255.255.0.
Select the Activate this scope check box, click OK, and then click Next.
On the Configure DHCPv6 Stateless Mode page, select Disable DHCPv6 stateless mode for this server, and then click Next.
On the Authorize DHCP Server page, select Use current credentials. Verify that CONTOSO\user1 is displayed next to Username, and then click Next.
On the Confirm Installation Selections page, click Install.
Verify the installation was successful, and then click Close.
Provision storage access on DHCP Server 1 and 2
Next, configure the iSCSI initiators on DHCP Server 1 and DHCP Server 2. To do this, launch the iSCSI Initiator Wizard from Administrative Tools.Complete the following steps on both DHCP Server 1 and DHCP Server 2.
To provision storage access on DHCP Server 1 and 2
Click Start, point to Administrative Tools and then click iSCSI Initiator.
Click Yes when prompted about the service not running, and then click Yes again when prompted to open Windows Firewall.
In iSCSI Initiator Properties, click Discovery, click Add Portal…, in IP Address or DNS Name type 172.16.1.1, in Port type 3260, and then click OK.
Click the Targets tab, click Log on…, check Automatically restore this connection when the computer starts, and then click OK.
Configure failover clustering on DHCP Server 1
Next, configure DHCP Server 1 and DHCP Server 2 for failover. You only need to complete these steps on DHCP Server 1.
To configure failover clustering on DHCP Server 1
Click Start, point to Administrative Tools and then click Failover Cluster Management.
Follow the Create Cluster Wizard directions, naming the cluster DHCPMCS.
Note
The wizard typically issues a validation warning and prompts you to run the validation tests to ensure that the systems chosen are compatible for the cluster configuration. It is strongly recommended that you run the tests.
Next, define the quorum for the cluster.
To start the Quorum Configuration Wizard, in the Failover Cluster Management tree, right-click dhcpmcs.contoso.com, point to More Actions, and then click Configure Cluster Quorum Settings….
In the Wizard, select Node and File Share Majority.
When prompted for the Shared Folder Path, type \\SS1.contoso.com\quorum.
Configure the DHCP service for failover clustering
The final step is to configure the DHCP service for failover clustering.
To Configure the DHCP Service for Failover Clustering
In the Failover Cluster Management console under DHCPMCS.contoso.com, click Configure a Service or Application.
Follow the High Availability Wizard directions, naming the Client Access PointDHCPMCSDhcp.
Now that DHCP is configured for failover, you can configure scopes and other options in the Failover Cluster Management console by right-clicking DHCPMCSDhcp under Services and Applications, and then clicking Manage DHCP.
Configure DHCP Client 1
DHCP Client 1 is a computer running Windows 7 that you will use to demonstrate a typical DHCP client that requests an IP Address from the DHCP servers in the cluster. The configuration is performed in the following steps:
Install the operating system.
Configure TCP/IP.
Verify network connectivity.
Join the computer to the domain and restart the computer.
Install Windows 7 client on DHCP Client1
To install the operating system on DHCP Client 1
Start your computer using the product disc for Windows 7.
When prompted for the installation type, choose Custom Installation.
When prompted for a computer name, type DHCP Client1.
On the Select your computer's current location page, click Work.
Follow the rest of the instructions that appear on your screen to finish the installation.
Configure TCP/IP on DHCP Client1
To configure TCP/IP on DHCP Client1
Click Start, and then click Control Panel.
Click Network and Internet, click Network and Sharing Center, and then click Manage network connections.
Right-click Local Area Connection, and then click Properties.
In the Local Area Connection Properties dialog box, clear the Internet Protocol Version 6 (TCP/IPv6) check box.
Click Internet Protocol Version 4 (TCP/IPv4), and then click Properties.
Verify that Obtain an IP address automatically and Obtain DNS server address automatically are selected.
Click OK, and then click Close to close the Local Area Connection Properties dialog box.
Close the Network Connections and Network and Sharing Center windows.
Join DHCP Client 1 to the Contoso.com domain
Because DHCP Client 1 now has access to domain services, it can be joined to the domain.
To join DHCP Client 1 to the Contoso.com domain
Click Start, right-click Computer, and then click Properties.
Under Computer name, domain, and workgroup settings, click Change settings.
In the System Properties dialog box, click Change.
In the Computer Name/Domain Changes dialog box, select Domain, and then type contoso.com and type enggmachine1.contoso.com in Computer Name.
Click More, and in Primary DNS suffix of this computer, type contoso.com.
Click OK twice.
When prompted for a user name and password, type the user name and password for User1 account, and then click OK.
When you see a dialog box that welcomes you to the Contoso.com domain, click OK.
When you see a dialog box that tells you that you must restart the computer to apply changes, click OK.
In the System Properties dialog box, click Close.
In the dialog box that prompts you to restart the computer, click Restart the computer now.
Renew the IP address of DHCP Client 1
Next, obtain a new IP address profile for DHCP Client 1 from the DHCP server.
To renew the IP address of DHCP Client 1
On DHCP Client 1, in the command prompt window, type ipconfig /renew, and then press ENTER.
At the command prompt, type ping 172.16.1.1, and then press ENTER.
Verify that the response reads “Reply from 172.16.1.1."
At the command prompt, type ipconfig, and then press ENTER.
In the command output, verify that the value of Connection-specific DNS Suffix is contoso.com and that the value of Subnet Mask is 255.255.255.0.
At the command prompt, type route print -4, and then press ENTER.
In the command output, below Active Routes, verify that a Network Destination of 172.16.1.1 is displayed.
Stop DHCP Server 1
To demonstrate that DHCP Server 2 will continue to distribute IP addresses to clients in the absence of DHCP Server 1, take DHCP Server 1 offline.
To stop the DHCP Server service on DHCP Server 1
- In the DHCP console tree, right-click DHCP Server 1, point to All Tasks and then click Stop.
Renew the IP addressing of DHCP Client 1
Next, obtain a new IP address profile for DHCP Client 1 from the DHCP server.
To renew the IP address of DHCP Client 1
On DHCP Client 1, in the command prompt window, type ipconfig /renew, and then press ENTER.
At the command prompt, type ping 172.16.1.1, and then press ENTER.
Verify that the response reads “Reply from 172.16.1.1."
At the command prompt, type ipconfig, and then press ENTER.
In the command output, verify that the value of Connection-specific DNS Suffix is contoso.com and that the value of Subnet Mask is 255.255.255.0.
At the command prompt, type route print -4, and then press ENTER.
In the command output, below Active Routes, verify that a Network Destination of 172.16.1.1 is displayed.
Appendix
This appendix will help you with troubleshooting techniques and the setting of optional features in Windows Server 2008 R2 and Windows 7.
Review DHCP client events
Reviewing information contained in DHCP client events can assist you with troubleshooting. It can also help you to understand DHCP client functionality.
To review DHCP client events in Event Viewer
Click Start, point to All Programs, click Accessories, and then click Run.
Type eventvwr.msc, and then press ENTER.
In the left tree, navigate to Event Viewer (Local)\Windows Logs\System).
Click an event in the middle pane.
By default, the General tab is displayed. Click the Details tab to view additional information.
You can also right-click an event and then click Event Properties to open a new window for reviewing events.