Host (Unix)

Last updated
host
Developer(s) Internet Systems Consortium (ISC)
Operating system Unix, Unix-like
Type Command
License Mozilla Public License 2.0

host is a simple utility for performing Domain Name System lookups.

Contents

Origin

It was developed by the Internet Systems Consortium (ISC), and is released under the Mozilla Public License 2.0. [1]

Modes

When applied to a fully qualified domain name (FQDN) the host command will return information associated with that name such as its IP address and mail handling host. It can also be used to list all members of a domain. [2] The host command is also able to perform reverse IP lookups to find the FQDN associated with an IP address. [3]

Example

$ host example.com example.com has address 93.184.216.34 example.com has IPv6 address 2606:2800:220:1:248:1893:25c8:1946 example.com mail is handled by 0 . 

See also

Related Research Articles

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 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.

BIND is a suite of software for interacting with the Domain Name System (DNS). Its most prominent component, named, performs both of the main DNS server roles, acting as an authoritative name server for DNS zones and as a recursive resolver in the network. As of 2015, it is the most widely used domain name server software, and is the de facto standard on Unix-like operating systems. Also contained in the suite are various administration tools such as nsupdate and dig, and a DNS resolver interface library.

A name server refers to the server component of the Domain Name System (DNS), one of the two principal namespaces of the Internet. The most important function of DNS servers is the translation (resolution) of human-memorable domain names (example.com) and hostnames into the corresponding numeric Internet Protocol (IP) addresses (192.0.2.1), the second principal name space of the Internet, which is used to identify and locate computer systems and resources on the Internet.

A mail exchanger record specifies the mail server responsible for accepting email messages on behalf of a domain name. It is a resource record in the Domain Name System (DNS). It is possible to configure several MX records, typically pointing to an array of mail servers for load balancing and redundancy.

A Domain Name System blocklist, Domain Name System-based blackhole list, Domain Name System blacklist (DNSBL) or real-time blackhole list (RBL) is a service for operation of mail servers to perform a check via a Domain Name System (DNS) query whether a sending host's IP address is blacklisted for email spam. Most mail server software can be configured to check such lists, typically rejecting or flagging messages from such sites.

<span class="mw-page-title-main">Root name server</span> Name server for the DNS root zone

A root name server is a name server for the root zone of the Domain Name System (DNS) of the Internet. It directly answers requests for records in the root zone and answers other requests by returning a list of the authoritative name servers for the appropriate top-level domain (TLD). The root name servers are a critical part of the Internet infrastructure because they are the first step in resolving human-readable host names into IP addresses that are used in communication between Internet hosts.

A wildcard DNS record is a record in a DNS zone that will match requests for non-existent domain names. A wildcard DNS record is specified by using a * as the leftmost label (part) of a domain name, e.g. *.example.com. The exact rules for when a wildcard will match are specified in RFC 1034, but the rules are neither intuitive nor clearly specified. This has resulted in incompatible implementations and unexpected results when they are used.

The Domain Name System Security Extensions (DNSSEC) is a suite of extension specifications by the Internet Engineering Task Force (IETF) for securing data exchanged in the Domain Name System (DNS) in Internet Protocol (IP) networks. The protocol provides cryptographic authentication of data, authenticated denial of existence, and data integrity, but not availability or confidentiality.

nslookup Utility to query the Domain Name System

nslookup is a network administration command-line tool for querying the Domain Name System (DNS) to obtain the mapping between domain name and IP address, or other DNS records.

In computer networking, a hostname is a label that is assigned to a device connected to a computer network and that is used to identify the device in various forms of electronic communication, such as the World Wide Web. Hostnames may be simple names consisting of a single word or phrase, or they may be structured. Each hostname usually has at least one numeric network address associated with it for routing packets for performance and other reasons.

A Canonical Name record is a type of resource record in the Domain Name System (DNS) that maps one domain name to another.

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.

In computer networks, a reverse DNS lookup or reverse DNS resolution (rDNS) is the querying technique of the Domain Name System (DNS) to determine the domain name associated with an IP address – the reverse of the usual "forward" DNS lookup of an IP address from a domain name. The process of reverse resolving of an IP address uses PTR records. rDNS involves searching domain name registry and registrar tables. The reverse DNS database of the Internet is rooted in the .arpa top-level domain.

Internet Systems Consortium, Inc., also known as ISC, is a Delaware-registered, 501(c)(3) non-profit corporation that supports the infrastructure of the universal, self-organizing Internet by developing and maintaining core production-quality software, protocols, and operations. ISC has developed several key Internet technologies that enable the global Internet, including: BIND, ISC DHCP and Kea. Other software projects no longer in active development include OpenReg and ISC AFTR.

Microsoft DNS is the name given to the implementation of domain name system services provided in Microsoft Windows operating systems.

<span class="mw-page-title-main">DNS zone</span> Part of the Internets Domain Name System (DNS) organization system

A DNS zone is a specific portion of the DNS namespace in the Domain Name System (DNS), which is managed by a specific organization or administrator. A DNS zone is an administrative space that allows for more granular control of the DNS components, such as authoritative nameserver. The DNS is broken up into many different zones, which are distinctly managed areas in the DNS namespace. DNS zones are not necessarily physically separated from one another, however, a DNS zone can contain multiple subdomains and multiple zones can exist on the same server.

DNS spoofing, also referred to as DNS cache poisoning, is a form of computer security hacking in which corrupt Domain Name System data is introduced into the DNS resolver's cache, causing the name server to return an incorrect result record, e.g. an IP address. This results in traffic being diverted to the attacker's computer.

A Domain Name System (DNS) zone file is a text file that describes a DNS zone. A DNS zone is a subset, often a single domain, of the hierarchical domain name structure of the DNS. The zone file contains mappings between domain names and IP addresses and other resources, organized in the form of text representations of resource records (RR). A zone file may be either a DNS master file, authoritatively describing a zone, or it may be used to list the contents of a DNS cache.

This article presents a comparison of the features, platform support, and packaging of many independent implementations of Domain Name System (DNS) name server software.

dig (command) Network administration command-line tool

dig is a network administration command-line tool for querying the Domain Name System (DNS).

References

  1. "BIND 9 Adopts the MPL 2.0 License with BIND 9.11.0 - Internet Systems Consortium". www.isc.org. Retrieved 2020-07-18.
  2. Jang, Michael (2009). Ubuntu Server Administration. McGraw Hill. p. 372. ISBN   978-0-07-159892-7.
  3. Maaẞen, Harald (2014). LPIC–2 Sicher zur erfolgreichen Linux-Zertifizierung (in German). Galileo Computing. pp. 304–305. ISBN   978-3-8362-2694-3.