Search domain

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A search domain is a domain used as part of a domain search list. The search list, as well as the local domain name, is used by a resolver to create a fully qualified domain name (FQDN) from a relative name. [1] For this purpose, the local domain name functions as a single-item search list.

Contents

IPv4

In an IPv4 environment, search domains are often set via DHCPv4, along with the local domain name. The domain search list is configured by the Domain Search Option (DHCPv4 option number 119), while the local domain name is configured by Domain Name (DHCPv4 option number 15). [2] [3]

The Windows operating system, however, understands the Domain Search Option only since Windows 10 April 2018 Update. [4] As a workaround for previous versions, many network administrators use Group Policy Objects to set the domain search list for Windows machines. [5]

IPv6

In an IPv6 environment, the domain search list is called a DNS Search List (DNSSL) and can be configured by Router Advertisement and DHCP. [6] [7]

Manually configuring domain search lists

In CentOS Linux search domain can be defined by editing the ifcfg file corresponding to the network. [8] In Mac OS X the setting is located under the DNS tab, next to DNS server settings. A similar setting in Microsoft Windows is the Connection-specific DNS Suffix.

Functionality

When looking up a bare name in DNS, the network stack will add the search domains to it to form fully qualified domain names, and look up those as well. [9] For example, if the domain search list contains "wikipedia.org", typing "en" in the browser will direct the user to "en.wikipedia.org". Some ISPs add their own search domains via DHCP settings, similar to how they add DNS servers and other networking information; if this is undesired, the user can change this setting to ".local" or a Top level domain.

Related Research Articles

The Domain Name System (DNS) is a hierarchical and distributed name service that provides a naming system for computers, services, and other resources in the Internet or other Internet Protocol (IP) networks. It associates various information with domain names assigned to each of the associated entities. Most prominently, it translates readily memorized domain names to the numerical IP addresses needed for locating and identifying computer services and devices with the underlying network protocols. The Domain Name System has been an essential component of the functionality of the Internet since 1985.

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.

An Internet Protocol address is a numerical label such as 192.0.2.1 that is assigned to a device connected to a computer network that uses the Internet Protocol for communication. IP addresses serve two main functions: network interface identification, and location addressing.

<span class="mw-page-title-main">IPv6</span> Version 6 of the Internet Protocol

Internet Protocol version 6 (IPv6) is the most recent version of the Internet Protocol (IP), the communications protocol that provides an identification and location system for computers on networks and routes traffic across the Internet. IPv6 was developed by the Internet Engineering Task Force (IETF) to deal with the long-anticipated problem of IPv4 address exhaustion, and was intended to replace IPv4. In December 1998, IPv6 became a Draft Standard for the IETF, which subsequently ratified it as an Internet Standard on 14 July 2017.

Dynamic DNS (DDNS) is a method of automatically updating a name server in the Domain Name System (DNS), often in real time, with the active DDNS configuration of its configured hostnames, addresses or other information.

The Bootstrap Protocol (BOOTP) is a computer networking protocol used in Internet Protocol networks to automatically assign an IP address to network devices from a configuration server. The BOOTP was originally defined in RFC 951 published in 1985.

Zero-configuration networking (zeroconf) is a set of technologies that automatically creates a usable computer network based on the Internet Protocol Suite (TCP/IP) when computers or network peripherals are interconnected. It does not require manual operator intervention or special configuration servers. Without zeroconf, a network administrator must set up network services, such as Dynamic Host Configuration Protocol (DHCP) and Domain Name System (DNS), or configure each computer's network settings manually.

<span class="mw-page-title-main">Preboot Execution Environment</span> Standard for booting from a server

In computing, the Preboot eXecution Environment, PXE specification describes a standardized client–server environment that boots a software assembly, retrieved from a network, on PXE-enabled clients. On the client side it requires only a PXE-capable network interface controller (NIC), and uses a small set of industry-standard network protocols such as DHCP and TFTP.

In Internet networking, a private network is a computer network that uses a private address space of IP addresses. These addresses are commonly used for local area networks (LANs) in residential, office, and enterprise environments. Both the IPv4 and the IPv6 specifications define private IP address ranges.

The Web Proxy Auto-Discovery (WPAD) Protocol is a method used by clients to locate the URL of a configuration file using DHCP and/or DNS discovery methods. Once detection and download of the configuration file is complete, it can be executed to determine the proxy for a specified URL.

The Neighbor Discovery Protocol (NDP), or simply Neighbor Discovery (ND), is a protocol of the Internet protocol suite used with Internet Protocol Version 6 (IPv6). It operates at the internet layer of the Internet model, and is responsible for gathering various information required for network communication, including the configuration of local connections and the domain name servers and gateways.

In computer networking, the multicast DNS (mDNS) protocol resolves hostnames to IP addresses within small networks that do not include a local name server. It is a zero-configuration service, using essentially the same programming interfaces, packet formats and operating semantics as unicast Domain Name System (DNS). It was designed to work as either a stand-alone protocol or compatible with standard DNS servers. It uses IP multicast User Datagram Protocol (UDP) packets and is implemented by the Apple Bonjour and open-source Avahi software packages, included in most Linux distributions. Although the Windows 10 implementation was limited to discovering networked printers, subsequent releases resolved hostnames as well. mDNS can work in conjunction with DNS Service Discovery (DNS-SD), a companion zero-configuration networking technique specified separately in RFC 6763.

The domain name .local is a special-use domain name reserved by the Internet Engineering Task Force (IETF) so that it may not be installed as a top-level domain in the Domain Name System (DNS) of the Internet. As such it is similar to the other special domain names, such as .localhost. However, .local has since been designated for use in link-local networking, in applications of multicast DNS (mDNS) and zero-configuration networking (zeroconf) so that DNS service may be established without local installations of conventional DNS infrastructure on local area networks.

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In computer networking, a link-local address is a network address that is valid only for communications on a local link, i.e. within a subnetwork that a host is connected to. Link-local addresses are most often unicast network addresses assigned automatically through a process known as stateless address autoconfiguration (SLAAC) or link-local address autoconfiguration, also known as automatic private IP addressing (APIPA) or auto-IP. Link-local addresses are not all unicast; e.g. IPv6 addresses beginning with ff02:, and IPv4 addresses beginning with 224.0.0. are multicast addresses that are link-local.

The Router Advertisement Daemon (radvd) is an open-source software product that implements link-local advertisements of IPv6 router addresses and IPv6 routing prefixes using the Neighbor Discovery Protocol (NDP) as specified in RFC 2461.

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<span class="mw-page-title-main">IPv6 address</span> Label to identify a network interface of a computer or other network node

An Internet Protocol version 6 address is a numeric label that is used to identify and locate a network interface of a computer or a network node participating in a computer network using IPv6. IP addresses are included in the packet header to indicate the source and the destination of each packet. The IP address of the destination is used to make decisions about routing IP packets to other networks.

Port Control Protocol (PCP) is a computer networking protocol that allows hosts on IPv4 or IPv6 networks to control how the incoming IPv4 or IPv6 packets are translated and forwarded by an upstream router that performs network address translation (NAT) or packet filtering. By allowing hosts to create explicit port forwarding rules, handling of the network traffic can be easily configured to make hosts placed behind NATs or firewalls reachable from the rest of the Internet, which is a requirement for many applications.

References

  1. ↑ Mockapetris, P.V. (November 1987). "Domain names - concepts and facilities" (HTML). IETF Documents. IETF. doi:10.17487/RFC1034 . Retrieved 24 July 2017. Relative names are either taken relative to a well known origin, or to a list of domains used as a search list. Relative names appear mostly at the user interface, where their interpretation varies from implementation to implementation, and in master files, where they are relative to a single origin domain name. The most common interpretation uses the root "." as either the single origin or as one of the members of the search list, so a multi-label relative name is often one where the trailing dot has been omitted to save typing.
  2. ↑ Bernard, Aboba; Stuart, Cheshire (November 2002). "RFC 3397 - Dynamic Host Configuration Protocol (DHCP) Domain Search Option" (HTML). IETF Documents. IETF. doi:10.17487/RFC3397 . Retrieved 22 July 2017.
  3. ↑ Alexander, Steve; Droms, Ralph (March 1997). "DHCP Options and BOOTP Vendor Extensions" (HTML). IETF Documents. section 3.17: IETF: 10. doi: 10.17487/RFC2132 . Retrieved 24 July 2017. 3.17. Domain Name
    This option specifies the domain name that client should use when resolving hostnames via the Domain Name System.
    The code for this option is 15.    {{cite journal}}: CS1 maint: location (link)
  4. ↑ "What's New in DHCP". Microsoft Learn. 2021-07-29. Retrieved 2024-01-13.
  5. ↑ Zuba, Matt (16 March 2011). "Windows Server 2008 RC2 DHCP Server Option 119 - Matt Zuba". Matt Zuba. Retrieved 22 July 2017.
  6. ↑ Jeong, Jaehoon; Park, Soohong; Beloeil, Luc; Madanapalli, Syam (2017). "RFC 8106 - IPv6 Router Advertisement Options for DNS Configuration" (HTML). IETF Documents. IETF. doi:10.17487/RFC8106 . Retrieved 4 December 2019.
  7. ↑ Droms, Ralph (2003). Droms, R. (ed.). "RFC 3646 - DNS Configuration options for Dynamic Host Configuration Protocol for IPv6 (DHCPv6)" (HTML). IETF Documents. IETF. doi: 10.17487/RFC3646 . Retrieved 24 July 2017.
  8. ↑ "How can I add additional search domains to the resolv.conf created by dhclient in CentOS". Super User. Retrieved 2016-12-18.
  9. ↑ "OS X Mountain Lion: Edit DNS and search domain settings". Apple Support. 4 September 2015. Retrieved 22 July 2017.

See also


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