{ "content": [ { "type": "text", "text": "# HOST (man)\n\n## NAME\n\nhost - DNS lookup utility\n\n## SYNOPSIS\n\nhost [-aACdlnrsTUwv] [-c class] [-N ndots] [-p port] [-R number] [-t type] [-W wait] [-m\nflag] [ [-4] | [-6] ] [-v] [-V] {name} [server]\n\n## DESCRIPTION\n\nhost is a simple utility for performing DNS lookups. It is normally used to convert names to\nIP addresses and vice versa. When no arguments or options are given, host prints a short sum‐\nmary of its command-line arguments and options.\n\n## TLDR\n\n> Lookup Domain Name Server.\n\n- Lookup A, AAAA, and MX records of a domain:\n `host {{domain}}`\n- Lookup a field (CNAME, TXT, ...) of a domain:\n `host -t {{field}} {{domain}}`\n- Reverse lookup an IP:\n `host {{ip_address}}`\n- Specify an alternate DNS server to query:\n `host {{domain}} {{8.8.8.8}}`\n\n*Source: tldr-pages*\n\n## Sections\n\n- **NAME**\n- **SYNOPSIS**\n- **DESCRIPTION**\n- **OPTIONS** (20 subsections)\n- **IDN SUPPORT**\n- **FILES** (1 subsections)\n- **SEE ALSO**\n- **AUTHOR**\n- **COPYRIGHT**\n\nUse structuredContent.sections for detailed options, examples, and full documentation.\n" } ], "structuredContent": { "command": "HOST", "section": "", "mode": "man", "summary": "host - DNS lookup utility", "synopsis": "host [-aACdlnrsTUwv] [-c class] [-N ndots] [-p port] [-R number] [-t type] [-W wait] [-m\nflag] [ [-4] | [-6] ] [-v] [-V] {name} [server]", "tldr_summary": "Lookup Domain Name Server.", "tldr_examples": [ { "description": "Lookup A, AAAA, and MX records of a domain", "command": "host {{domain}}" }, { "description": "Lookup a field (CNAME, TXT, ...) of a domain", "command": "host -t {{field}} {{domain}}" }, { "description": "Reverse lookup an IP", "command": "host {{ip_address}}" }, { "description": "Specify an alternate DNS server to query", "command": "host {{domain}} {{8.8.8.8}}" } ], "tldr_source": "official", "flags": [ { "flag": "-4", "long": null, "arg": null, "description": "-6 option." }, { "flag": "-6", "long": null, "arg": null, "description": "-4 option." }, { "flag": "-a", "long": null, "arg": null, "description": "ior of the -l list zone option." }, { "flag": "-A", "long": null, "arg": null, "description": "records are omitted from the output." }, { "flag": "-c", "long": null, "arg": null, "description": "This option specifies the query class, which can be used to lookup HS (Hesiod) or CH (Chaosnet) class resource records. The default class is IN (Internet)." }, { "flag": "-C", "long": null, "arg": null, "description": "the SOA records for zone name from all the listed authoritative name servers for that zone. The list of name servers is defined by the NS records that are found for the zone." }, { "flag": "-d", "long": null, "arg": null, "description": "" }, { "flag": "-l", "long": null, "arg": null, "description": "transfer of zone name and prints out the NS, PTR, and address records (A/AAAA). Together, the -l -a options print all records in the zone." }, { "flag": "-N", "long": null, "arg": null, "description": "This option specifies the number of dots (ndots) that have to be in name for it to be considered absolute. The default value is that defined using the ndots statement in /etc/resolv.conf, or 1 if no ndots statement is present. Names with fewer dots are in‐ terpreted as relative names, and are searched for in the domains listed in the search or domain directive in /etc/resolv.conf." }, { "flag": "-p", "long": null, "arg": null, "description": "This option specifies the port to query on the server. The default is 53." }, { "flag": "-r", "long": null, "arg": null, "description": "sion desired) bit in the query. This means that the name server receiving the query does not attempt to resolve name. The -r option enables host to mimic the behavior of a name server by making non-recursive queries, and expecting to receive answers to those queries that can be referrals to other name servers." }, { "flag": "-R", "long": null, "arg": null, "description": "This option specifies the number of retries for UDP queries. If number is negative or zero, the number of retries is silently set to 1. The default value is 1, or the value of the attempts option in /etc/resolv.conf, if set." }, { "flag": "-s", "long": null, "arg": null, "description": "sponds with a SERVFAIL response, which is the reverse of normal stub resolver behav‐ ior." }, { "flag": "-t", "long": null, "arg": null, "description": "This option specifies the query type. The type argument can be any recognized query type: CNAME, NS, SOA, TXT, DNSKEY, AXFR, etc. When no query type is specified, host automatically selects an appropriate query type. By default, it looks for A, AAAA, and MX records. If the -C option is given, queries are made for SOA records. If name is a dotted-decimal IPv4 address or colon-delimited IPv6 address, host queries for PTR records. If a query type of IXFR is chosen, the starting serial number can be specified by ap‐ pending an equals sign (=), followed by the starting serial number, e.g., -t IXFR=12345678." }, { "flag": "-U", "long": null, "arg": null, "description": "-T option makes it use a TCP connection when querying the name server. TCP is automat‐ ically selected for queries that require it, such as zone transfer (AXFR) requests. Type ANY queries default to TCP, but can be forced to use UDP initially via -U." }, { "flag": "-m", "long": null, "arg": null, "description": "This option sets memory usage debugging: the flag can be record, usage, or trace. The -m option can be specified more than once to set multiple flags." }, { "flag": "-v", "long": null, "arg": null, "description": "output can also be enabled by setting the debug option in /etc/resolv.conf." }, { "flag": "-V", "long": null, "arg": null, "description": "" }, { "flag": "-w", "long": null, "arg": null, "description": "also the -W option." }, { "flag": "-W", "long": null, "arg": null, "description": "This options sets the length of the wait timeout, indicating that named should wait for up to wait seconds for a reply. If wait is less than 1, the wait interval is set to 1 second. By default, host waits for 5 seconds for UDP responses and 10 seconds for TCP connec‐ tions. These defaults can be overridden by the timeout option in /etc/resolv.conf. See also the -w option." } ], "examples": [], "see_also": [ { "name": "dig", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/dig/1/json" }, { "name": "named", "section": "8", "url": "https://www.chedong.com/phpMan.php/man/named/8/json" } ], "section_outline": [ { "name": "NAME", "lines": 2, "subsections": [] }, { "name": "SYNOPSIS", "lines": 3, "subsections": [] }, { "name": "DESCRIPTION", "lines": 10, "subsections": [] }, { "name": "OPTIONS", "lines": 1, "subsections": [ { "name": "-4", "lines": 2, "flag": "-4" }, { "name": "-6", "lines": 2, "flag": "-6" }, { "name": "-a", "lines": 2, "flag": "-a" }, { "name": "-A", "lines": 2, "flag": "-A" }, { "name": "-c class", "lines": 3, "flag": "-c" }, { "name": "-C", "lines": 4, "flag": "-C" }, { "name": "-d", "lines": 1, "flag": "-d" }, { "name": "-l", "lines": 4, "flag": "-l" }, { "name": "-N ndots", "lines": 6, "flag": "-N" }, { "name": "-p port", "lines": 2, "flag": "-p" }, { "name": "-r", "lines": 5, "flag": "-r" }, { "name": "-R number", "lines": 4, "flag": "-R" }, { "name": "-s", "lines": 3, "flag": "-s" }, { "name": "-t type", "lines": 12, "flag": "-t" }, { "name": "-T, -U", "lines": 4, "flag": "-U" }, { "name": "-m flag", "lines": 3, "flag": "-m" }, { "name": "-v", "lines": 2, "flag": "-v" }, { "name": "-V", "lines": 1, "flag": "-V" }, { "name": "-w", "lines": 2, "flag": "-w" }, { "name": "-W wait", "lines": 9, "flag": "-W" } ] }, { "name": "IDN SUPPORT", "lines": 6, "subsections": [] }, { "name": "FILES", "lines": 1, "subsections": [ { "name": "/etc/resolv.conf", "lines": 1 } ] }, { "name": "SEE ALSO", "lines": 2, "subsections": [] }, { "name": "AUTHOR", "lines": 2, "subsections": [] }, { "name": "COPYRIGHT", "lines": 6, "subsections": [] } ], "sections": { "NAME": { "content": "host - DNS lookup utility\n", "subsections": [] }, "SYNOPSIS": { "content": "host [-aACdlnrsTUwv] [-c class] [-N ndots] [-p port] [-R number] [-t type] [-W wait] [-m\nflag] [ [-4] | [-6] ] [-v] [-V] {name} [server]\n", "subsections": [] }, "DESCRIPTION": { "content": "host is a simple utility for performing DNS lookups. It is normally used to convert names to\nIP addresses and vice versa. When no arguments or options are given, host prints a short sum‐\nmary of its command-line arguments and options.\n\nname is the domain name that is to be looked up. It can also be a dotted-decimal IPv4 address\nor a colon-delimited IPv6 address, in which case host by default performs a reverse lookup\nfor that address. server is an optional argument which is either the name or IP address of\nthe name server that host should query instead of the server or servers listed in /etc/re‐‐\nsolv.conf.\n", "subsections": [] }, "OPTIONS": { "content": "", "subsections": [ { "name": "-4", "content": "-6 option.\n", "flag": "-4" }, { "name": "-6", "content": "-4 option.\n", "flag": "-6" }, { "name": "-a", "content": "ior of the -l list zone option.\n", "flag": "-a" }, { "name": "-A", "content": "records are omitted from the output.\n", "flag": "-A" }, { "name": "-c class", "content": "This option specifies the query class, which can be used to lookup HS (Hesiod) or CH\n(Chaosnet) class resource records. The default class is IN (Internet).\n", "flag": "-c" }, { "name": "-C", "content": "the SOA records for zone name from all the listed authoritative name servers for that\nzone. The list of name servers is defined by the NS records that are found for the\nzone.\n", "flag": "-C" }, { "name": "-d", "content": "", "flag": "-d" }, { "name": "-l", "content": "transfer of zone name and prints out the NS, PTR, and address records (A/AAAA).\n\nTogether, the -l -a options print all records in the zone.\n", "flag": "-l" }, { "name": "-N ndots", "content": "This option specifies the number of dots (ndots) that have to be in name for it to be\nconsidered absolute. The default value is that defined using the ndots statement in\n/etc/resolv.conf, or 1 if no ndots statement is present. Names with fewer dots are in‐\nterpreted as relative names, and are searched for in the domains listed in the search\nor domain directive in /etc/resolv.conf.\n", "flag": "-N" }, { "name": "-p port", "content": "This option specifies the port to query on the server. The default is 53.\n", "flag": "-p" }, { "name": "-r", "content": "sion desired) bit in the query. This means that the name server receiving the query\ndoes not attempt to resolve name. The -r option enables host to mimic the behavior of\na name server by making non-recursive queries, and expecting to receive answers to\nthose queries that can be referrals to other name servers.\n", "flag": "-r" }, { "name": "-R number", "content": "This option specifies the number of retries for UDP queries. If number is negative or\nzero, the number of retries is silently set to 1. The default value is 1, or the value\nof the attempts option in /etc/resolv.conf, if set.\n", "flag": "-R" }, { "name": "-s", "content": "sponds with a SERVFAIL response, which is the reverse of normal stub resolver behav‐\nior.\n", "flag": "-s" }, { "name": "-t type", "content": "This option specifies the query type. The type argument can be any recognized query\ntype: CNAME, NS, SOA, TXT, DNSKEY, AXFR, etc.\n\nWhen no query type is specified, host automatically selects an appropriate query type.\nBy default, it looks for A, AAAA, and MX records. If the -C option is given, queries\nare made for SOA records. If name is a dotted-decimal IPv4 address or colon-delimited\nIPv6 address, host queries for PTR records.\n\nIf a query type of IXFR is chosen, the starting serial number can be specified by ap‐\npending an equals sign (=), followed by the starting serial number, e.g., -t\nIXFR=12345678.\n", "flag": "-t" }, { "name": "-T, -U", "content": "-T option makes it use a TCP connection when querying the name server. TCP is automat‐\nically selected for queries that require it, such as zone transfer (AXFR) requests.\nType ANY queries default to TCP, but can be forced to use UDP initially via -U.\n", "flag": "-U" }, { "name": "-m flag", "content": "This option sets memory usage debugging: the flag can be record, usage, or trace. The\n-m option can be specified more than once to set multiple flags.\n", "flag": "-m" }, { "name": "-v", "content": "output can also be enabled by setting the debug option in /etc/resolv.conf.\n", "flag": "-v" }, { "name": "-V", "content": "", "flag": "-V" }, { "name": "-w", "content": "also the -W option.\n", "flag": "-w" }, { "name": "-W wait", "content": "This options sets the length of the wait timeout, indicating that named should wait\nfor up to wait seconds for a reply. If wait is less than 1, the wait interval is set\nto 1 second.\n\nBy default, host waits for 5 seconds for UDP responses and 10 seconds for TCP connec‐\ntions. These defaults can be overridden by the timeout option in /etc/resolv.conf.\n\nSee also the -w option.\n", "flag": "-W" } ] }, "IDN SUPPORT": { "content": "If host has been built with IDN (internationalized domain name) support, it can accept and\ndisplay non-ASCII domain names. host appropriately converts character encoding of a domain\nname before sending a request to a DNS server or displaying a reply from the server. To turn\noff IDN support, define the IDNDISABLE environment variable. IDN support is disabled if the\nvariable is set when host runs.\n", "subsections": [] }, "FILES": { "content": "", "subsections": [ { "name": "/etc/resolv.conf", "content": "" } ] }, "SEE ALSO": { "content": "dig(1), named(8).\n", "subsections": [] }, "AUTHOR": { "content": "Internet Systems Consortium\n", "subsections": [] }, "COPYRIGHT": { "content": "2026, Internet Systems Consortium\n\n\n\n\n9.18.39-0ubuntu0.22.04.4-Ubuntu 2025-08-13 HOST(1)", "subsections": [] } } } }