--- name: "host" section: "1" platform: "linux" package: "bind" version: "9.20.30-1" release: "Arch Linux 2026-11-01" platforms: ["linux", "freebsd", "openbsd", "macos"] url: "https://new.carta.tech/host" --- # host(1) DNS lookup utility ## NAME host - DNS lookup utility ## SYNOPSIS **host** \[**-aACdlnrsTUwv**\] \[**-c** class\] \[**-N** ndots\] \[**-p** port\] \[**-R** number\] \[**-t** type\] \[**-W** wait\] \[**-m** flag\] \[ \[**-4**\] \| \[**-6**\] \] \[**-v**\] \[**-V**\] {name} \[server\] ## DESCRIPTION **host** is a simple utility for performing DNS lookups. It is normally used to convert names to IP addresses and vice versa. When no arguments or options are given, **host** prints a short summary of its command-line arguments and options. **name** is the domain name that is to be looked up. It can also be a dotted-decimal IPv4 address or a colon-delimited IPv6 address, in which case **host** by default performs a reverse lookup for that address. **server** is an optional argument which is either the name or IP address of the name server that **host** should query instead of the server or servers listed in **/etc/resolv.conf**. ## OPTIONS - **-4** This option specifies that only IPv4 should be used for query transport. See also the **-6** option. - **-6** This option specifies that only IPv6 should be used for query transport. See also the **-4** option. - **-a** The **-a** ("all") option is normally equivalent to **-v** **-t ANY**. It also affects the behavior of the **-l** list zone option. - **-A** The **-A** ("almost all") option is equivalent to **-a**, except that RRSIG, NSEC, and NSEC3 records are omitted from the output. - **-c class** 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). - **-C** This option indicates that **named** \<#std-iscman-named\> should check consistency, meaning that **host** queries 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. - **-d** This option prints debugging traces, and is equivalent to the **-v** verbose option. - **-l** This option tells **named** \<#std-iscman-named\> to list the zone, meaning the **host** command performs a zone 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. - **-N ndots** 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 interpreted as relative names, and are searched for in the domains listed in the **search** or **domain** directive in **/etc/resolv.conf**. - **-p port** This option specifies the port to query on the server. The default is 53. - **-r** This option specifies a non-recursive query; setting this option clears the RD (recursion 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. - **-R number** 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. - **-s** This option tells **named** \<#std-iscman-named\> *not* to send the query to the next nameserver if any server responds with a SERVFAIL response, which is the reverse of normal stub resolver behavior. - **-t type** 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, MX, and HTTPS 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 appending an equals sign (=), followed by the starting serial number, e.g., **-t IXFR=12345678**. - **-T, -U** This option specifies TCP or UDP. By default, **host** uses UDP when making queries; the **-T** option makes it use a TCP connection when querying the name server. TCP is automatically 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**. - **-m flag** 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. - **-v** This option sets verbose output, and is equivalent to the **-d** debug option. Verbose output can also be enabled by setting the **debug** option in **/etc/resolv.conf**. - **-V** This option prints the version number and exits. - **-w** This option sets "wait forever": the query timeout is set to the maximum possible. See also the **-W** option. - **-W wait** This options sets the length of the wait timeout, indicating that **named** \<#std-iscman-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 connections. These defaults can be overridden by the **timeout** option in **/etc/resolv.conf**. See also the **-w** option. ## IDN SUPPORT If **host** has been built with IDN (internationalized domain name) support, it can accept and display non-ASCII domain names. **host** appropriately converts character encoding of a domain name before sending a request to a DNS server or displaying a reply from the server. To turn off IDN support, define the **IDN\_DISABLE** environment variable. IDN support is disabled if the variable is set when **host** runs. ## FILES **/etc/resolv.conf** ## SEE ALSO **[dig(1)](/dig/1.md)** \<#std-iscman-dig\>, **[named(8)](/named/8.md)** \<#std-iscman-named\>. ## Author Internet Systems Consortium ## Copyright 2026, Internet Systems Consortium