Such agents relay messages between DHCP clients and DHCP servers located on different subnets.ĭepending on implementation, the DHCP server may have three methods of allocating IP addresses:ĭynamic allocation A network administrator reserves a range of IP addresses for DHCP, and each DHCP client on the LAN is configured to request an IP address from the DHCP server during network initialization. On large networks that consist of multiple links, a single DHCP server may service the entire network when aided by DHCP relay agents located on the interconnecting routers. When a DHCP client refreshes an assignment, it initially requests the same parameter values, but the DHCP server may assign a new address based on the assignment policies set by administrators. A DHCP client typically queries for this information immediately after booting, and periodically thereafter before the expiration of the information. On receiving a DHCP request, the DHCP server may respond with specific information for each client, as previously configured by an administrator, or with a specific address and any other information valid for the entire network and for the time period for which the allocation ( lease) is valid. The DHCP server manages a pool of IP addresses and information about client configuration parameters such as default gateway, domain name, the name servers, and time servers. Any DHCP server on the network may service the request.
#What is dhcp client id software
When a computer or other device connects to a network, the DHCP client software sends a DHCP broadcast query requesting the necessary information. A DHCP server can manage IP settings for devices on its local network, e.g., by assigning IP addresses to those devices automatically and dynamically.ĭHCP operates based on the client–server model. Internet Protocol (IP) defines how devices communicate within and across local networks on the Internet. After updates by many subsequent RFCs, it was replaced with RFC 8415, which merged in prefix delegation, and stateless address autoconfiguration. ĭHCPv6 was initially described by RFC 3315 in 2003. DHCP was first defined in RFC 1531 in October 1993, but due to errors in the editorial process was almost immediately reissued as RFC 1541.įour years later the DHCPINFORM message type and other small changes were added by RFC 2131, which as of 2021 remains the core of the standard for IPv4 networks, with updates in RFC 3396, RFC 4361, RFC 5494, and RFC 6842. It can also be used to deliver a wide range of extra configuration parameters to IP clients, including platform-specific parameters. ĭHCP is based on BOOTP, but can dynamically allocate IP addresses from a pool and reclaim them when they are no longer in use. This introduced the concept of a relay agent, which allowed the forwarding of BOOTP packets across networks, allowing one central BOOTP server to serve hosts on many IP subnets. RARP was superseded by the Bootstrap Protocol ( BOOTP) defined in RFC 951 in September 1985. It required that a server be present on each individual network link. Acting in the data link layer it made implementation difficult in many server platforms. The Reverse Address Resolution Protocol (RARP) was defined in RFC 903 in 1984 for the configuration of simple devices, such as diskless workstations, with a suitable IP address. 5.2.1 Relay agent information sub-options.The IPv6 version of the DHCP protocol is commonly called DHCPv6. Within a local network, a DHCP server assigns a local IP address to each device.ĭHCP services exist for networks running Internet Protocol version 4 (IPv4), as well as version 6 ( IPv6). Most residential network routers receive a unique IP address within the ISP network. Many routers and residential gateways have DHCP server capability. When connected to the network, and periodically thereafter, a client requests a set of parameters from the DHCP server using the DHCP protocol.ĭHCP can be implemented on networks ranging in size from residential networks to large campus networks and regional ISP networks. The technology eliminates the need for individually configuring network devices manually, and consists of two network components, a centrally installed network DHCP server and client instances of the protocol stack on each computer or device. The Dynamic Host Configuration Protocol ( DHCP) is a network management protocol used on Internet Protocol (IP) networks for automatically assigning IP addresses and other communication parameters to devices connected to the network using a client–server architecture.
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