The answer to “What is DHCP?” is that it’s the standard mechanism to dynamically assign IP addresses within a network. It stands for Dynamic Host Configuration Protocol. Show
IP, or Internet Protocol, addressing is a logical means of assigning addresses to devices on a network. Each device connected to a network requires a unique IP address. At home, dynamic host configuration protocol (DHCP) assigns IP addresses to your smartphones, laptops, tablets, and devices like doorbell cameras. When you use wifi on your home network, typically your router is a DHCP server. In a large enterprise setting, a DHCP server is usually a dedicated computer. By simplifying IP address management, it saves money, is more secure, and doesn’t eat up valuable admin time. In this glossary entry, we’ll explore the fundamentals of how DHCP works. Then, we’ll take a deeper look at two aspects: dynamic addressing and the communications protocol. How does DHCP work?DHCP is a network management protocol. A client device (or DHCP client), such as a laptop, joins a network and requests an IP address. The request is made to a DHCP server. These servers are often configured with redundancy—often called DHCP failover—or clustering among other network servers. Servers can run on both IPv4 and IPv6 networks.  The server will quickly and automatically assign an IP address and some related network configuration parameters. Once the device has accepted the assignment, it can communicate with both the internal network and the public internet. Relevant parametersIn addition to assigning IP addresses, these servers also provide relevant parameters, known as DHCP options. The Internet Assigned Numbers Authority (IANA), the global coordinator of IP addresses, defines available DHCP parameters. Options number in the hundreds. Key among them is how long the IP address can be used—known as the lease time. They also include the default gateway, its subnet mask, and its DNS server. Some additional definitionsTo clarify, let’s quickly define some of these terms we just mentioned:
Dynamic IP addressing with DHCPThe assignment of IP addresses happens dynamically within a given address range. As a result, a device connected to the network doesn’t have a forever address. The IP address can periodically change as its lease time expires unless the lease is successfully renewed. For services that always need to be on, a static IP address is often a better option. Corporate enterprises commonly use static IP addresses for hardware like mail servers. Certainly, a DHCP server should have a static IP address. However, there are drawbacks to dedicating a specific IP address to a device or service. A network administrator must manually assign, configure, and track the IP address. It’s a time-consuming task. Oftentimes, it requires the admin to physically be with the device. Meanwhile, dynamic IP addresses are usually the preferred choice because they:
DHCP communications protocolCommunications to fulfill a DHCP request involves both the server and client. Furthermore, a relay agent or IP helper often facilitates communication between the two. Relay agents receive broadcast DHCP messages from clients and then re-send those messages with configuration information to servers. Communication happens via small units of data, called packets, that are routed through a network. Networking protocols like IP govern all its rules. Most of the time, communication occurs in four steps. Briefly, they are:
With this in mind, one final point: DHCP alongside DNS and IP address management (IPAM) are together known as DDI. Want to know how to define DDI or how it works to form a complete management solution? The BlueCat platform is the place to start. Related content
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This eBook outlines the journey from the functional to the inevitable, when you realize your free DNS is anything but. See how both tactical and strategic… What does DHCP server can provide for the IP addresses?A DHCP Server is a network server that automatically provides and assigns IP addresses, default gateways and other network parameters to client devices. It relies on the standard protocol known as Dynamic Host Configuration Protocol or DHCP to respond to broadcast queries by clients.
What is the IP address of the DHCP server?The DHCP server determines the configuration based on the client's hardware address as specified in the CHADDR (client hardware address) field. In the following example the server (192.168. 1.1) specifies the client's IP address in the YIADDR (your IP address) field.
Does DHCP automatically assign IP addresses?Dynamic Host Configuration Protocol (DHCP) is a network protocol that enables a server to automatically assign an IP address to a computer from a defined range of numbers (that is, a scope) configured for a given network.
What is the role of the DHCP server?A DHCP server dynamically assigns an IP address and other network configuration parameters to each device on a network so they can communicate with other IP networks. DHCP is an enhancement of an older protocol called BOOTP.
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