183 lines
6.6 KiB
Plaintext
183 lines
6.6 KiB
Plaintext
.\" Man page generated from reStructuredText.
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.TH "HOST" "1" "@RELEASE_DATE@" "@BIND9_VERSION@" "BIND 9"
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.SH NAME
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host \- DNS lookup utility
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..
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.SH SYNOPSIS
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.sp
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\fBhost\fP [\fB\-aACdlnrsTUwv\fP] [\fB\-c\fP class] [\fB\-N\fP ndots] [\fB\-p\fP port] [\fB\-R\fP number] [\fB\-t\fP type] [\fB\-W\fP wait] [\fB\-m\fP flag] [ [\fB\-4\fP] | [\fB\-6\fP] ] [\fB\-v\fP] [\fB\-V\fP] {name} [server]
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.SH DESCRIPTION
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.sp
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\fBhost\fP is a simple utility for performing DNS lookups. It is normally
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used to convert names to IP addresses and vice versa. When no arguments
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or options are given, \fBhost\fP prints a short summary of its command
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line arguments and options.
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.sp
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\fBname\fP is the domain name that is to be looked up. It can also be a
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dotted\-decimal IPv4 address or a colon\-delimited IPv6 address, in which
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case \fBhost\fP will by default perform a reverse lookup for that address.
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\fBserver\fP is an optional argument which is either the name or IP
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address of the name server that \fBhost\fP should query instead of the
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server or servers listed in \fB/etc/resolv.conf\fP\&.
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.SH OPTIONS
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.INDENT 0.0
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.TP
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\fB\-4\fP
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Use IPv4 only for query transport. See also the \fB\-6\fP option.
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.TP
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\fB\-6\fP
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Use IPv6 only for query transport. See also the \fB\-4\fP option.
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.TP
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\fB\-a\fP
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"All". The \fB\-a\fP option is normally equivalent to \fB\-v \-t ANY\fP\&. It
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also affects the behaviour of the \fB\-l\fP list zone option.
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.TP
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\fB\-A\fP
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"Almost all". The \fB\-A\fP option is equivalent to \fB\-a\fP except RRSIG,
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NSEC, and NSEC3 records are omitted from the output.
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.TP
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\fB\-c\fP class
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Query class: This can be used to lookup HS (Hesiod) or CH (Chaosnet)
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class resource records. The default class is IN (Internet).
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.TP
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\fB\-C\fP
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Check consistency: \fBhost\fP will query the SOA records for zone
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\fBname\fP from all the listed authoritative name servers for that
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zone. The list of name servers is defined by the NS records that are
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found for the zone.
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.TP
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\fB\-d\fP
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Print debugging traces. Equivalent to the \fB\-v\fP verbose option.
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.TP
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\fB\-l\fP
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List zone: The \fBhost\fP command performs a zone transfer of zone
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\fBname\fP and prints out the NS, PTR and address records (A/AAAA).
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.sp
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Together, the \fB\-l \-a\fP options print all records in the zone.
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.TP
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\fB\-N\fP ndots
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The number of dots that have to be in \fBname\fP for it to be
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considered absolute. The default value is that defined using the
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ndots statement in \fB/etc/resolv.conf\fP, or 1 if no ndots statement
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is present. Names with fewer dots are interpreted as relative names
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and will be searched for in the domains listed in the \fBsearch\fP or
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\fBdomain\fP directive in \fB/etc/resolv.conf\fP\&.
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.TP
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\fB\-p\fP port
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Specify the port on the server to query. The default is 53.
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.TP
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\fB\-r\fP
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Non\-recursive query: Setting this option clears the RD (recursion
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desired) bit in the query. This should mean that the name server
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receiving the query will not attempt to resolve \fBname\fP\&. The \fB\-r\fP
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option enables \fBhost\fP to mimic the behavior of a name server by
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making non\-recursive queries and expecting to receive answers to
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those queries that can be referrals to other name servers.
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.TP
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\fB\-R\fP number
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Number of retries for UDP queries: If \fBnumber\fP is negative or zero,
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the number of retries will default to 1. The default value is 1, or
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the value of the \fBattempts\fP option in \fB/etc/resolv.conf\fP, if set.
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.TP
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\fB\-s\fP
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Do \fInot\fP send the query to the next nameserver if any server responds
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with a SERVFAIL response, which is the reverse of normal stub
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resolver behavior.
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.TP
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\fB\-t\fP type
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Query type: The \fBtype\fP argument can be any recognized query type:
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CNAME, NS, SOA, TXT, DNSKEY, AXFR, etc.
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.sp
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When no query type is specified, \fBhost\fP automatically selects an
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appropriate query type. By default, it looks for A, AAAA, and MX
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records. If the \fB\-C\fP option is given, queries will be made for SOA
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records. If \fBname\fP is a dotted\-decimal IPv4 address or
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colon\-delimited IPv6 address, \fBhost\fP will query for PTR records.
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.sp
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If a query type of IXFR is chosen the starting serial number can be
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specified by appending an equal followed by the starting serial
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number (like \fB\-t IXFR=12345678\fP).
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.TP
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\fB\-T\fP; \fB\-U\fP
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TCP/UDP: By default, \fBhost\fP uses UDP when making queries. The
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\fB\-T\fP option makes it use a TCP connection when querying the name
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server. TCP will be automatically selected for queries that require
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it, such as zone transfer (AXFR) requests. Type ANY queries default
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to TCP but can be forced to UDP initially using \fB\-U\fP\&.
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.TP
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\fB\-m\fP flag
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Memory usage debugging: the flag can be \fBrecord\fP, \fBusage\fP, or
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\fBtrace\fP\&. You can specify the \fB\-m\fP option more than once to set
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multiple flags.
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.TP
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\fB\-v\fP
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Verbose output. Equivalent to the \fB\-d\fP debug option. Verbose output
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can also be enabled by setting the \fBdebug\fP option in
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\fB/etc/resolv.conf\fP\&.
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.TP
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\fB\-V\fP
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Print the version number and exit.
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.TP
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\fB\-w\fP
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Wait forever: The query timeout is set to the maximum possible. See
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also the \fB\-W\fP option.
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.TP
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\fB\-W\fP wait
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Timeout: Wait for up to \fBwait\fP seconds for a reply. If \fBwait\fP is
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less than one, the wait interval is set to one second.
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.sp
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By default, \fBhost\fP will wait for 5 seconds for UDP responses and 10
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seconds for TCP connections. These defaults can be overridden by the
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\fBtimeout\fP option in \fB/etc/resolv.conf\fP\&.
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.sp
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See also the \fB\-w\fP option.
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.UNINDENT
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.SH IDN SUPPORT
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.sp
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If \fBhost\fP has been built with IDN (internationalized domain name)
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support, it can accept and display non\-ASCII domain names. \fBhost\fP
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appropriately converts character encoding of domain name before sending
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a request to DNS server or displaying a reply from the server. If you\(aqd
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like to turn off the IDN support for some reason, define the IDN_DISABLE
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environment variable. The IDN support is disabled if the variable is set
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when \fBhost\fP runs.
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.SH FILES
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.sp
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\fB/etc/resolv.conf\fP
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.SH SEE ALSO
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.sp
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\fBdig(1)\fP, \fBnamed(8)\fP\&.
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.SH AUTHOR
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Internet Systems Consortium
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.SH COPYRIGHT
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2020, Internet Systems Consortium
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.\" Generated by docutils manpage writer.
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.
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