Member Servers or just standalone servers can be promoted to domain controller. The Active Directory Wizard can help you install and configure components and enables you to provide directory service to network computers and users.
A server on a network - standalone or member - can function in a number of roles. As the needs of your computing environment change, you may want to change the role of a server. By using the Server Manager and the Add Roles Wizard, you can install Active Directory Domain Servers to promote a member server to a domain controller, or you can install individual roles or combinations of various roles, such as DHCP, WINS, and DNS.
When you add a permanent entry to the DNS cache, it will always override the information provided by the nameserver. Here are a few reasons why you might want to do this.
If you use an Ethernet or Wi-Fi connection to access your network, you might find that Ubuntu spends a few seconds during each boot acquiring an Internet address. This will be characterized by a long pause while nothing seems to be happening. Therefore, one way to provide an instant speed boost is to give your computer a static IP address.