What service is used to automatically assign TCP IP configuration information to hosts?

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.[1]

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. When connected to the network, and periodically thereafter, a client requests a set of parameters from the server using DHCP.

DHCP can be implemented on networks ranging in size from residential networks to large campus networks and regional ISP networks.[2] Many routers and residential gateways have DHCP server capability. Most residential network routers receive a unique IP address within the ISP network. Within a local network, a DHCP server assigns a local IP address to each device.

DHCP services exist for networks running Internet Protocol version 4 [IPv4], as well as version 6 [IPv6]. The IPv6 version of the DHCP protocol is commonly called DHCPv6.

History[edit]

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. Acting in the data link layer it made implementation difficult in many server platforms. It required that a server be present on each individual network link. RARP was superseded by the Bootstrap Protocol [BOOTP] defined in RFC 951 in September 1985. 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.[3]

DHCP is based on BOOTP, but can dynamically allocate IP addresses from a pool and reclaim them when they are no longer in use. It can also be used to deliver a wide range of extra configuration parameters to IP clients, including platform-specific parameters.[4] 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.

Four years later the DHCPINFORM message type[5] 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.[6]

DHCPv6 was initially described by RFC 3315 in 2003. After updates by many subsequent RFCs,[7] it was replaced with RFC 8415, which merged in prefix delegation, and stateless address autoconfiguration.

Overview[edit]

Internet Protocol [IP] defines how devices communicate within and across local networks on the Internet. 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.

DHCP operates based on the client–server model. When a computer or other device connects to a network, the DHCP client software sends a DHCP broadcast query requesting the necessary information. Any DHCP server on the network may service the request. 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. 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. A DHCP client typically queries for this information immediately after booting, and periodically thereafter before the expiration of the information. 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.

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. Such agents relay messages between DHCP clients and DHCP servers located on different subnets.

Depending on implementation, the DHCP server may have three methods of allocating IP addresses:

Dynamic allocationA 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. The request-and-grant process uses a lease concept with a controllable time period, allowing the DHCP server to reclaim and then reallocate IP addresses that are not renewed.Automatic allocationThe DHCP server permanently assigns an IP address to a requesting client from a range defined by an administrator. This is like dynamic allocation, but the DHCP server keeps a table of past IP address assignments, so that it can preferentially assign to a client the same IP address that the client previously had.Manual allocationThis method is also variously called static DHCP allocation, fixed address allocation, reservation, and MAC/IP address binding. An administrator maps a unique identifier [a client id or MAC address] for each client to an IP address, which is offered to the requesting client. DHCP servers may be configured to fall back to other methods if this fails.

DHCP services are used for Internet Protocol version 4 [IPv4] and IPv6. The details of the protocol for IPv4 and IPv6 differ sufficiently that they may be considered separate protocols.[8] For the IPv6 operation, devices may alternatively use stateless address autoconfiguration. IPv6 hosts may also use link-local addressing to achieve operations restricted to the local network link.

Operation[edit]

Boot Service Discovery Protocol [BSDP] – a DHCP extension used by Apple's NetBoot

Comparison of DHCP server software

Peg DHCP [RFC 2322]

Preboot Execution Environment [PXE]

Reverse Address Resolution Protocol [RARP]

Rogue DHCP

UDP Helper Address – a tool for routing DHCP requests across subnet boundaries

Zeroconf – Zero Configuration Networking

Notes[edit]

^ a b As an optional client behavior, some broadcasts, such as those carrying DHCP discovery and request messages, may be replaced with unicasts in case the DHCP client already knows the DHCP server's IP address.[10]
^ The RFC calls for the client to wait one half of the remaining time until T2 before it retransmits the DHCPREQUEST packet
^ The proposal provided a mechanism whereby two servers could remain loosely in sync with each other in such a way that even in the event of a total failure of one server, the other server could recover the lease database and continue operating. Due to the length and complexity of the specification, it was never published as a standard; however, the techniques described in the proposal are in wide use, with open-source and several commercial implementations.

References[edit]

^ Gillis, Alexander S. "What is DHCP [Dynamic Host Configuration Protocol]?". TechTarget: SearchNetworking. Retrieved 19 February 2021.
^ Peterson, Larry L.; Davie, Bruce S. [2011]. Computer Networks: A Systems Approach [5th ed.]. Elsevier. ISBN 978-0123850607. Retrieved March 21, 2019.
^ Bill Croft; John Gilmore [September 1985]. "RFC 951 - Bootstrap Protocol". Network Working Group. doi:10.17487/RFC0951.
^ Network+ Certification 2006 Published By Microsoft Press.
^ used for the Web Proxy Autodiscovery Protocol Web Proxy Autodiscovery Protocol [WPAD]
^ Droms, R. [March 1997]. "Dynamic Host Configuration Protocol". doi:10.17487/RFC2131. Retrieved 2 December 2021.
^ RFC 4361, RFC 5494, RFC 6221, RFC 6422, RFC 6644, RFC 7083, RFC 7227, RFC 7283
^ Droms, Ralph; Lemon, Ted [2003]. The DHCP Handbook. SAMS Publishing. p. 436. ISBN 978-0-672-32327-0.
^ a b Droms, Ralph [March 1997]. "Dynamic Host Configuration Protocol". tools.ietf.org. doi:10.17487/RFC2131. Retrieved 4 July 2017.
^ a b c d e f g h i R. Droms [March 1997]. Dynamic Host Configuration Protocol. Network Working Group. doi:10.17487/RFC2131. RFC 2131. Draft Standard. Obsoletes RFC 1541.
^ Droms, Ralph [March 1997]. "RFC2131 Dynamic Host Configuration Protocol: Dynamic allocation of network addresses". tools.ietf.org. doi:10.17487/RFC2131.
^ a b "Dynamic Host Configuration Protocol [DHCP] and Bootstrap Protocol [BOOTP] Parameters". iana.org. Retrieved 2018-10-16.
^ a b c d e f g h i j k l m n o p Alexander, Steve; Droms, Ralph [March 1997]. DHCP options and BOOTP vendor extensions. IETF. doi:10.17487/RFC2132. RFC 2132. Retrieved June 10, 2012.
^ a b T'joens, Yves; De Schrijver, Peter [December 2001]. DHCP reconfigure extension. IETF. doi:10.17487/RFC3203. RFC 3203. Retrieved November 13, 2020.
^ a b c d e Woundy, Rich; Kinnear, Kim [February 2006]. DHCP reconfigure extension. IETF. doi:10.17487/RFC4388. RFC 4388. Retrieved November 13, 2020.
^ a b c Kinnear, Kim; Stapp, Mark; Rao, D.T.V Ramakrishna; Joshi, Bharat; Russell, Neil; Kurapati, Pavan; Volz, Bernie [April 2013]. DHCP reconfigure extension. IETF. doi:10.17487/RFC6926. RFC 6926. Retrieved November 13, 2020.
^ a b c d Kinnear, Kim; Stapp, Mark; Volz, Bernie; Russell, Neil [December 2015]. DHCP reconfigure extension. IETF. doi:10.17487/RFC7724. RFC 7724. Retrieved November 13, 2020.
^ a b c d Patrick, Michael [January 2001]. "DHCP Relay Agent Information Option". IETF Documents. IETF. doi:10.17487/RFC3046. Retrieved 22 July 2017.
^ a b c Provan, Don [November 1997]. "RFC 2241 – DHCP Options for Novell Directory Services". IETF Documents. IETF. doi:10.17487/RFC3256. Retrieved 23 July 2017.
^ a b Lear, E.; Eggert, P. [April 2007]. "Timezone Options for DHCP". IETF Documents. IETF. doi:10.17487/RFC4833. Retrieved 28 June 2018.
^ Kumari, Warren. "RFC 8910 - Captive-Portal Identification in DHCP and Router Advertisements [RAs]". ietf.org. IETF. Retrieved 25 March 2021.
^ Bernard, Aboba; Stuart, Cheshire [November 2002]. "RFC 3397 – Dynamic Host Configuration Protocol [DHCP] Domain Search Option". IETF Documents. IETF. doi:10.17487/RFC3397. Retrieved 22 July 2017.
^ Lemon, T.; Cheshire, S.; Volz, B. [2002]. "RFC 3442". doi:10.17487/RFC3442.
^ a b c Hankins, David [December 2007]. "RFC 5071 - Dynamic Host Configuration Protocol Options Used by PXELINUX". ietf.org. IETF. doi:10.17487/RFC5071. Retrieved 25 March 2021.
^ Doug, Jones; Rich, Woundy [April 2002]. "RFC 3256 – The DOCSIS [Data-Over-Cable Service Interface Specifications] Device Class DHCP [Dynamic Host Configuration Protocol] Relay Agent Information Sub-option". IETF Documents. IETF. doi:10.17487/RFC3256. Retrieved 23 July 2017.
^ Droms, Ralph; Kinnear, Kim; Stapp, Mark; Volz, Bernie; Gonczi, Steve; Rabil, Greg; Dooley, Michael; Kapur, Arun [March 2003]. DHCP Failover Protocol. IETF. I-D draft-ietf-dhc-failover-12. Retrieved May 9, 2010.
^ Weinberg, Neal [2018-08-14]. "Why DHCP's days might be numbered". Network World. Retrieved 2019-08-07.
^ a b Patrick, Michael [January 2001]. "RFC 3046 - DHCP Relay Agent Information Option". Network Working Group. doi:10.17487/RFC3046.
^ a b c d Droms, Ralph [March 1997]. "RFC 2131 - Dynamic Host Configuration Protocol". Network Working Group. doi:10.17487/RFC2131.
^ a b c Stapko, Timothy [2011]. Practical Embedded Security: Building Secure Resource-Constrained Systems. Newnes. p. 39. ISBN 978-0-08-055131-9.
^ Rountree, Derrick [2013]. Windows 2012 Server Network Security: Securing Your Windows Network Systems and Infrastructure. Newnes. p. 22. ISBN 978-1-59749-965-1.
^ Rooney, Timothy [2010]. Introduction to IP Address Management. John Wiley & Sons. p. 180. ISBN 978-1-118-07380-3.
^ a b Golovanov [Kaspersky Labs], Sergey [June 2011]. "TDSS loader now got "legs"". Archived from the original on 25 January 2021.
^ Hens, Francisco J.; Caballero, José M. [2008]. Triple Play: Building the converged network for IP, VoIP and IPTV. John Wiley & Sons. p. 239. ISBN 978-0-470-75439-9.
^ Ramirez, David H. [2008]. IPTV Security: Protecting High-Value Digital Contents. John Wiley & Sons. p. 55. ISBN 978-0-470-72719-5.
^ Lemon, Ted [April 2002]. "Implementation of RFC 3118".
^ Golden, Philip; Dedieu, Hervé; Jacobsen, Krista S. [2007]. Implementation and Applications of DSL Technology. Taylor & Francis. p. 484. ISBN 978-1-4200-1307-8.
^ Rooney, Timothy [2010]. Introduction to IP Address Management. John Wiley & Sons. pp. 181–182. ISBN 978-1-118-07380-3.
^ Copeland, Rebecca [2008]. Converging NGN Wireline and Mobile 3G Networks with IMS. Taylor & Francis. pp. 142–143. ISBN 978-1-4200-1378-8.
^ Prasad, Ramjee; Mihovska, Albena [2009]. New Horizons in Mobile and Wireless Communications: Networks, services, and applications. Vol. 2. Artech House. p. 339. ISBN 978-1-60783-970-5.
^ "Draft-pruss-DHCP-auth-DSL-07 - EAP Authentication Extensions for the Dynamic Host Configuration Protocol for Broadband". Archived from the original on 2015-04-03. Retrieved 2013-12-12.

External links[edit]

Media related to Dynamic Host Configuration Protocol [DHCP] at Wikimedia Commons

What methods are used to assign TCP IP parameters to host?

Using DHCP A TCP/IP host uses the DHCP [Dynamic Host Configuration Protocol] to obtain its configuration parameters [IP address, gateway, name servers, and so on] from a DHCP server that contains the configuration parameters of all the hosts on the network.

What is used to automatically assign an IP address to a client?

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.

Which of the following is used to automate the IP configuration of network hosts?

Dynamic Host Configuration Protocol. Dynamic Host Configuration Protocol [DHCP] is a network management protocol used to automate the process of configuring devices on IP networks, thus allowing them to use network services such as DNS, NTP, and any communication protocol based on UDP or TCP.

Which service helps in getting IP automatically?

A Windows-based computer that is configured to use DHCP can automatically assign itself an Internet Protocol [IP] address if a DHCP server is not available. For example, this could occur on a network without a DHCP server, or on a network if a DHCP server is temporarily down for maintenance.