About Dynamic Host Configuration Protocol (DHCP) Server
A Dynamic Host Configuration Protocol (DHCP) server is a computer that has Windows Server 2008 R2 installed on it, and is responsible for assigning IP addresses to the computers automatically. IP addresses assigned to the computers by DHCP server are known as dynamic IP addresses, and the computers that are configured to obtain the IP addresses automatically from the DHCP server are called DHCP client computers.
During DHCP server configuration, administrators specify a range of IP addresses in the DHCP scope. All IP addresses that fall within the specified range are stored in IP Address Pool. Every time a DHCP client computer requests an IP address from a DHCP server, the server randomly picks up any one of the available IP addresses from its address pool and assigns it to the requesting client computer. This process is known as dynamic IP address assignment.
Dynamic Host Configuration Protocol (DHCP) IP Address Assignment Process
The process of IP address assignment completes in four steps called DORA where D represents DHCP Discover, O represents DHCP Offer, R represents DHCP Request and A represents DHCP Acknowledge. Description of DORA is as below:
- DHCP Discover – DHCP Discover is a broadcast packet that is sent from a DHCP client computer. DHCP Discover packet is broadcasted to search for all available DHCP servers in the network. Since it is a broadcast packet, it is received by all the computers connected to the network (including all available DHCP servers) without exceptions.
- DHCP Offer – DHCP Offer is a unicast packet that is sent from the DHCP server to the requesting DHCP client computer in response to the received broadcasted DHCP Discover packet. DHCP Offer packet contains an available IP address from the address pool, offering it to the requesting DHCP client computer.
- DHCP Request – DHCP Request is a unicast packet sent from a DHCP client computer to a DHCP server from which it has received DHCP Offer packet. DHCP client computer sends DHCP Request packet requesting the DHCP server to assign the offered IP address.
- DHCP Acknowledge – DHCP Acknowledge is a unicast packet sent from the DHCP server to the DHCP client computer confirming the successful assignment of the requested IP address.
Prerequisites for Installing DHCP Server Role
Before DHCP server role is installed on a Windows Server 2008 R2 computer, administrators must verify that:
- The computer that is to be configured as DHCP server has been assigned with a static IP address.
- A DNS zone has been created on any network operating system in the network if no domain controller is present.
Install and Configure Dynamic Host Configuration Protocol (DHCP) on Windows Server 2008 R2
To install and configure Dynamic Host Configuration Protocol (DHCP) on Windows Server 2008 R2, administrators must follow the steps given as below:
- Log on to Windows Server 2008 R2 computer with the domain administrator or enterprise administrator account credentials on which DHCP server is to be installed and configured.
- Make sure that the computer has been assigned with a static IP address.
- Ensure that the DNS server is available anywhere in the network and is properly configured.
- On the desktop screen, click Server Manager icon from the taskbar.
- On the Server Manager window, from the console tree in the left, make sure that Roles option is selected.
- On the right pane, make sure that the Roles Summary section is expanded.
- From the expanded section, click Add Roles.
- On Add Roles Wizard window, click Next.
- On Select Server Roles page, from the Roles list, check DHCP Server checkbox and click Next.
- On the DHCP Server page, click Next.
- On Select Network Connection Bindings page, make sure that the IP address representing the network connection that is to be bound is checked from the Network Connectionslist.
- Click Next to continue.
- On Specify IPv4 DNS Server Settings page, populate the Preferred DNS serer IPv4 address and optional Alternate DNS server IPv4 address fields with the correct values.
- Once specified, click Validate to confirm the availability of DNS server and click Next.
- On Specify IPv4 WINS Server Settings page, leave everything as default and click Next.
- On Add or Edit DHCP Scopes page, click Add.
- On Add Scope box, populate the Scope name, Starting IP address, and Ending IP address fields with the desired values and click OK.
- Back on Add or Edit DHCP Scope page, click Next.
- On Configure DHCPv6 Stateless Mode page, leave everything as default and click Next.
- On Specify IPv6 DNS Server Settings page, leave everything as default (assuming that the network setup doesn’t have IPv6 addressing scheme) and click Next to proceed.
- On Authorize DHCP Server page, make sure that the Use current credentials radio button is selected. Alternatively, Use alternate credentialsradio button can also be selected to specify the domain admin credentials that is to be allowed to authorize DHCP server in AD DS.
Note: Authorize DHCP Server page will be displayed only when an Active Directory Domain Controller is present in the network. In case the Active Directory Domain Controller is absent, the page is not displayed.
- Click Next to proceed.
- On Confirm Installation Selections page, review the settings and click Install to start the DHCP installation and configuration process.
- Once installed, click Close on the Installation Results page.
- Close Server Manager window when done.