A search domain is a domain used as part of a domain search list. The domain 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.
For this purpose, the local domain name functions as a single-item search list.
IPv4
In an IPv4 environment, search domains are often set via
DHCPv4
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 cli ...
, 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).
The Windows operating system, however, does not understand the Domain Search Option; as a workaround, many network administrators use Group Policy Objects to set the domain search list for Windows machines.
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.
Manually configuring domain search lists
In CentOS Linux search domain can be defined by editing the ifcfg file corresponding to the network.
In
Mac OS X
macOS (; previously OS X and originally Mac OS X) is a Unix operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac (computer), Mac computers. Within the market of ...
the setting is located under the
DNS
The Domain Name System (DNS) is a hierarchical and distributed 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 ...
tab, next to DNS server settings. A similar setting in
Microsoft Windows
Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for serv ...
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.
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
An Internet service provider (ISP) is an organization that provides services for accessing, using, or participating in the Internet. ISPs can be organized in various forms, such as commercial, community-owned, non-profit, or otherwise private ...
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".
References
See also
*
Domain Name System
The Domain Name System (DNS) is a hierarchical and distributed 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 ...
*
DHCP Options
Domain Name System
Network service
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