A DHCP server is an application, or rather a service, that automatically assigns an IP address to an member of the network that needs an IP address.

In Microsoft Windows Server 2008 R2, a DHCP server is a role. This means that you must first install Microsoft Windows Server 2008, and then add the DHCP server.

You don't have to use a DHCP server, especially in a small network where you can easily manage the job of assigning and maintaining IP addresses. If you decide to use a DHCP server, you should (highly recommended) provide a static IP address to the computer (the DNS server). We have already seen how:

When setting up a DHCP server, you can indicate the number of IP addresses that will be necessary for your network. For example, imagine you are creating a small network for home or a small business. The maximum number of computers you will possibly use is 10, 20, or 50. The number of available IP addresses goes from one minimum to a maximum. This is referred to as the range of IP addresses.

As stated already, the range of IP addresses must start from a certain minimum. Let's take an example of 192.168.1.10. If you know that you will have at most 50 computers in your network, the possible maximum IP address you would need is 192.168.1.60.

To install the DHCP server after starting Microsoft Windows Server 2008 R2 and logging in with an account that has administrative rights:

1. In the Initial Configuration Tasks, click Add Roles.
   As an alternative, you could click Start -> Administrative Tools. In the left frame, right-click Roles and click Add Roles
2. In the first page of the wizard, titled Before You Begin, read the text and click Next
3. In the second page of the wizard, click the check box of DHCP Server
    
   
4. Click Next
    
   
5. In the third page of the wizard, click Next
6. The 4th page of the wizard shows the IP address that was assigned to the server during primary configuration:
    
   
    

   Click Next

7. The next page shows the web domain and the DNS IP address(es).
   You can accept the default preferred to DNS and click Validate
    
   
    

   If you don't like or don't want that IP address, provide your own and click Validate

8. Click Next. The page allows you to specify a WINS server or not:
    
   
9. After specifying the WINS or to skip it, click Next
10. The next page allows you to optionally specify a range of IP addresses.
    If you don't want to specify a range of IP addresses (we will not use it for our small network), click Next:
     
    
    
    If you want to specify a range of IP addresses, click Add...
    1. In the Scope Name, type a name (anything using letters and digits), such as LocalizedSegment, and press Tab
    2. In the Starting IP Address text box, type the lowest address of the desired range and press Tab
    3. In the Ending IP Address text box, the highest IP address
        
       
    4. Click OK
        
       
    5. Click Next
    The next page asks you whether you want to use IPv6 or not:
     
    
11. Click Next
     
    
12. Click Next.
    The next page asks you to specify what account is used to validate the installation
     
    
13. Click Next.
    The next page shows a summary of your selections before the actual installation (the contents of the dialog box will depend on whether you provided a range or IP addresses or not):
     
    
14. Click Install.
    The installation will start. This may take a few minutes. When the installation is over, click Close:
     
    

As stated already, the job of the DHCP server is to automatically assign IP addresses to any member of the network that needs an IP address.

A DHCP server assigns an IP address to a computer when that computer starts. If the computer has already started and if the computer was previously given an IP address, if that IP address is out of the range of allowed IP addresses, the computer may loose connected to the server. In this case, you must change the IP address of the computer.

To manually change the IP address of a computer:

1. Click Start -> Control Panel
2. Click Network and Internet
3. Click Network and Sharing Center
4. Click Local Area Connection (or Network Connection, depending on your computer)
5. Click Properties.
   You may be asked to provide a user name and a password. In this case, start with the name of the computer, followed by \, followed by an account that has local admin rights, and press Tab. If the account uses a password, type it. When ready, click Yes
6. In the Networking tab of the Local Area Connection Properties, in the checked list box, click Internet Protocol Version 4 (TCP/IPv4)
    
   
7. Click Properties
8. Click Obtain An IP Address Automatically
9. Click Obtain DNS Server Address Automatically
    
   
10. Click Advanced
     
    
11. Click OK
12. Click OK
13. Click Close
14. Click Close

To automatically change the IP address of a computer:

1. Click Start, type cmd and press Enter
2. Type ipconfig /renew and press Enter