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Lesson 7 DHCP and Static IP
Objective Explain the differences between dynamic and static IP addressing.

DHCP and Static IP

IP addresses are either static or dynamic. Something static rarely changes. So, a static IP address on a client rarely changes. A dynamic IP address issued to a client is just the opposite. It changes each time the client connects to the network (or Internet).

IP addresses

You have to consider the cons if you issue a static IP address. The first is record keeping. You have to keep voluminous records of every IP address for every client in your organization. Then, you need to consistently update the list, making adjustments where necessary. Second is reconfiguring each client. If ever your IP address scheme changes, you have to go back and reconfigure every client by hand. If you have a large organization, say of 50 clients, this can be an arduous task. Last, the IP address protocol is 32 bits long. As more and more users across the world join the Internet, there are fewer unique addresses left, so administrators can conserve address allocation by only assigning them to users currently connected to the network (or Internet).

Dynamic IP addresses

Larger networks use dynamic IP addressing because they can afford the automation equipment associated with dynamic addressing. For example, think of a network in a college. The system administrator might dynamically assign IP addresses to students' computers located in the residence halls. Dynamic Host Configuration Protocol (DHCP) is the protocol used to automatically assign IP addresses. The server simply issues the IP address as needed.

How DHCP works

Your client initially requests an IP address from the DHCP server. The DHCP server then scans its list, finds an available IP address, and issues it to the client. The client then uses that address until it expires. Expiration can be set to a particular time, but it's typically valid until the user logs off.
The primary advantage of DHCP is that system administrators no longer have to manually assign IP addresses to every computer.
Either way, the IP protocol permits network administrators the option to statically assign an IP address or to automatically assign an IP address (dynamic IP address, using DHCP).
The table below describes these options.
In the next lesson, you will learn how to configure your browser for best performance.

Type of IP Address Description
Static
  1. Permanent IP address
  2. Can be assigned to clients or servers in a TCP/IP network
  3. Usually assigned to servers and other devices that serve multiple network users, such as printers
Dynamic
  1. Automatically assigned to a client in a TCP/IP network
  2. Usually assigned from a DHCP server
  3. Can specify a time period for which the IP address will be available