With
technology budgets shrinking and more demand being put on IT staff to
provide business solutions, there is a need to automate normal IT
functions and make management easier. One of the often-overlooked but
perhaps most efficient time-saving tool is the DHCP Server role. As
with the DNS Server role, this role is not automatically installed and
needs to be added to your Windows Server 2008 server in order to lease
IP addresses to workstations. Let’s look at installing the DHCP Server
role and take a look at how to configure it on a network.
To install the DHCP Server role, perform the following steps:
1. | Launch the Server Manager, scroll down to the roles summary, and click Add roles.
| 2. | After
the Add Roles Wizard launches, choose the DHCP Server role from the
selections. You will notice immediately that the wizard populates with
seven options on the left side of the screen:
Click Next to begin the installation of DHCP.
| 3. | On
the next screen, which provides an overview of the DHCP Server role,
information about DHCP and IP addressing (Things to Note), and links to
additional information about DHCP in Windows Server 2008, click Next.
| 4. | Check
the bindings of DHCP to ensure that you have a static IP address for
the server. Here you have the option of allowing different network
cards to service DHCP clients on separate subnets. Check the IP
addresses and type (IPv4 or IPv6) and recheck the details to ensure
that you are binding the correct IP address to the correct adapter.
Click Next.
| 5. | Set
the parent domain as well as the preferred and alternate DNS servers.
Also validate that the preferred and alternate DNS servers are correct
and online. Figure 1 shows a valid preferred DNS server and an invalid alternate DNS server. Click Next.
| 6. | Choose
whether to use WINS on the network and insert your preferred and
alternate WINS server IP addresses. Most newer clients and applications
do not require WINS, so accept the default, WINS Is Not Required and
click Next.
| 7. | Choose the DHCP scope(s). Click Add and then provide the following:
Scope name (for example, rare-tech) Starting IP address Ending IP address Subnet mask Default gateway Subnet type: Wired (with a lease duration of 6 days) or Wireless (with a lease duration of 8 hours)
Check the box to activate the scope (unchecking would not activate the
scope) and click OK. Finally, add additional scopes, if needed, and
click Next.
| 8. | Set
the option to enable or disable the IPv6 stateless mode for the DHCP
server. Either DHCPv6 can assign IPv6 addresses or the clients can be
configured automatically. When you’re done making your selection, click
Next.
Note
When
choosing how to handle address leases with DHCPv6, keep in mind that
whichever method you choose (stateful or stateless), if the router you
are using supports IPv6, the settings in the router must match the
settings in the DHCP server.
| 9. | As
with IPv4, set the parent domain as well as the preferred and alternate
DNS servers. Then validate the DNS servers and click Next.
| 10. | Choose
the credentials that will be used to authorize with Active Directory
Domain Services (AD DS): You can use the current credentials, choose
alternate credentials, or choose to skip authorization with AD DS.
Click Next.
| 11. | When
you see the confirmation page to review all your DHCP selections before
installing the DHCP Server role, if everything matches with your
specifications, click Install.
| 12. | Finally, when you see that the installation is successful and that DHCP can now be configured in the DHCP Manager, click Close.
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With
the DHCP Server role installed, you are now ready to lease IP addresses
to clients connected to your Windows Server 2008 server.
Configure Additional Settings in DHCP
Although
the DHCP Server role is functional when installation is complete, there
are still some configurations to make to the DHCP server. In fact, in
some cases (perhaps when decommissioning an old DHCP server), you might
not have activated a new DHCP server you installed on your server. So
let’s examine how to activate and finish the configuration of DHCP in
Windows Server 2008. To configure the DHCP Server role, perform the
following steps:
1. | Select Start, Server Manager or Administrative Tools, DHCP Manager.
| 2. | Highlight the DHCP server and select the Actions menu. Here you can configure some key items, including the following:
- Add/Remove Bindings: This is useful if network cards were added, removed, or configured after the initial installation.
- Unauthorize: You can remove the authorization of the DHCP server in this directory.
- Backup: You can back up the configuration and the database.
- Restore: You can restore the configuration and the database.
- All Tasks: You can start, stop, pause, resume, or restart the DHCP Server role service.
- Properties: You can view or change the location of the DHCP database and backup files.
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We’ll
now move on to configuring the settings for IPv4 and IPv6. Because many
of the options are the same, and IPv4 is still the dominant protocol,
we will look at the settings from an IPv4 perspective. Throughout the
section, we highlight where the differences exist, using notes titled
“For IPv6.”
Configure IPv4 and IPv6 Settings
This
section looks at the options you can configure for IPv4 in the DHCP
Server role. Because these settings are unique to each network, this
section serves as an overview of available options. To begin
configuring IPv4, in the DHCP Manager, expand the DHCP server and
highlight IPv4. Next click the Actions menu, and you see several
options for configuring and managing IPv4:
Display Statistics:
Shows DHCP server statistics, including uptime, requests, declines,
total scopes, total addresses, and percentages of addresses in use and
available. New Scope: Sets up a scope for delivering IP addresses to clients. New SuperScope: Allows you to group several divergent scopes under a logical name. New Multicast Scope:
Allows the sending of messages to select clients connected to the
network without adding overhead and without disturbing clients that are
not listening. Define User Classes: Adds a class for clients that need similar DHCP options. Define Vendor Classes: Adds a class for clients that have a specific vendor type (for example, Windows 98, Windows 2000). Reconcile All Scopes:
Compares scope information with the registry. In addition, corrects and
repairs any inconsistencies found within the scopes examined. Set Predefined Options:
Verifies and sets options for IPv4 in the DHCP server, such as the
router, time server, log server, IP layer forwarding, and so on. Properties: Specifies properties, in four tabs: General:
In this tab you can configure when the statistics are updated, in hours
and minutes, enable DHCP audit logging, and show the BOOTP table folder. DNS:
Here you can enable DNS dynamic updates (always or only if requested),
discard A and PTR records when a lease is deleted, and enable dynamic
updates for legacy (Windows NT 4.0) clients. Network Access Protection: In this tab you can enable or disable NAP. You can also set the behavior of the DHCP server when NPS is unavailable. Advanced:
On this tab you can configure the number of times DHCP should attempt
conflict detection before leasing an IP address. You can also verify
and change the audit log file path for DHCP. Again, you can change the
connection bindings for network cards. Finally, you can configure the
credentials for dynamic DNS updates to the DHCP server.
Note
For IPv6:
In the IPv6 properties page, there is not a Network Access Protection
tab because security is built in to the protocol. On the Advanced tab,
there are no conflict detection settings because IPv6 by design does
not experience conflict errors.
Configuring Scope Options
After
you have created scopes (superscopes or multiscopes), you still have
some options you can configure in the DHCP Manager. Some options
available are similar to the server-level configurations. At the scope
level, you can view the statistics, reconcile the scope, and set
properties. You can also activate or deactivate scopes. If you did not
activate the scope during installation of the DHCP Server role, you
should activate the scope here. Figure 2 shows a scope activation.
The properties page is again broken down into four tabs:
General:
In this tab you can set the scope name, starting and ending IP
addresses, lease duration, and whether the lease is limited (days,
hours, minutes) or unlimited. DNS:
In this tab you can enable DNS dynamic updates (always or only if
requested), discard A and PTR records when a lease is deleted, and
enable dynamic updates for legacy (Windows NT 4.0) clients. Network Access Protection: This tab allows you to enable or disable NAP and choose to use a default or custom profile. Advanced:
This tab lets you configure options for leasing to DHCP, BOOTP clients,
or both. You can also set the lease duration for BOOTP clients.
Note
For IPv6:
At the scope level, there are a few differences on the properties page.
On the DNS tab, there is no support for dynamic updates for legacy
clients. Again, there is no Network Access Protection tab. The Advanced
tab is replaced with the Lease tab, where you can configure settings
for temporary and non-temporary addresses. In addition, you can
configure both the preferred and valid lifetimes in days, hours, and
minutes.
Besides the scope options, you can configure and manage the following options:
Address Pool: You can add exclusion ranges for IP addresses. Address Leases: You can view active leases, the expiration date, and the status of NAP. Reservations:
You can add reservations to clients that you want to ensure have the
same IP address when DHCP renews its lease with the client machine. Scope or Server Options:
You can assign options that apply to all scopes (server options) or
clients within a scope (scope options). Some assigned options are DNS
servers, routers, time servers, mail servers, and so on.
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