What Is Dynamic Host Configuration Protocol – DHCP?
Dynamic Host Configuration Protocol works in a client/server mode. DHCP enables clients on an IP network to obtain or lease IP addresses or configurations from a DHCP server. This reduces workload when managing a large network. DHCP protocol is described in the RFC 2131.
Most modern operating system includes DHCP in their primary settings, these includes Windows OS, Novell NetWare, Sun Solaris, Linux, and Mac OS. The clients’ requests for addressing configuration from a DHCP network server, the network server manages the assignment of IP addresses and must be obliged to answer any IP configuration requests from clients.
However, network routers, switches, and servers need to have static IP addresses, DHCP is not intended for the configuration of these types of hosts. Cisco routers use a Cisco IOS feature known as Cisco Easy IP Lease. This offers an optional but full-featured DHCP server. Easy IP leases address for 24hrs by default, it is most useful in homes and small offices where users can take advantage of DHCP and NAT without having an NT or UNIX server
The DHCP server uses User Datagram Protocol (UTP) as its transport protocol to send messages to the client on port 68, while the client uses port 67 to send messages to the server.
DHCP servers can offer other information, this includes, DNS server addresses, WINS server addresses, and domain names. In most DHCP servers, administrators are allowed to define clients’ MAC addresses, which the server automatically assigns the same IP, address each time.
Key Components of DHCP
DHCP Server: This is a network server that holds and manages the pool of IP addresses and configuration information. It responds to requests from clients, assigning IP addresses and configuration details.
DHCP Client: Any device that requests and uses configuration information from a DHCP server, typically a computer, smartphone, or other networked devices.
IP Address Pool: A range of IP addresses managed by the DHCP server and assigned to clients.
DHCP Lease: The temporary assignment of an IP address to a client. The lease has a fixed duration and can be renewed.
How DHCP Works
The DHCP process involves four primary steps, often referred to as DORA (Discover, Offer, Request, Acknowledge):
Discover: The client broadcasts a discover message to find available DHCP servers when it connects to the network.
Offer: DHCP servers respond to the discover message with an offer message that contains an available IP address and other network configuration details.
Request: The client responds to the offer it chooses (in case of multiple offers) with a request message, indicating that it would like to accept the offered configuration.
Acknowledge: The DHCP server sends an acknowledgment packet to the client, confirming the lease of the IP address and other configuration details.
Most administrators prefer to work with a network server that offers DHCP services. These types of networks are scalable and easy to manage.
In summary, DHCP is an important protocol in modern networks, helps to simplify network administration by automating the assignment of IP addresses and other network settings. Its ability to efficiently manage IP resources makes it a standard feature in most business and consumer network environments.
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