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https://github.com/isc-projects/bind9.git
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407 lines
7.8 KiB
HTML
407 lines
7.8 KiB
HTML
<!--
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- Copyright (C) 2004 Internet Systems Consortium, Inc. ("ISC")
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- Copyright (C) 2000, 2001, 2003 Internet Software Consortium.
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-
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- Permission to use, copy, modify, and distribute this software for any
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- purpose with or without fee is hereby granted, provided that the above
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- copyright notice and this permission notice appear in all copies.
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-
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- THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
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- REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
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- AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
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- INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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- LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
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- OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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- PERFORMANCE OF THIS SOFTWARE.
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-->
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<!-- $Id: host.html,v 1.4.2.3 2004/08/22 23:35:39 marka Exp $ -->
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML
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><HEAD
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><TITLE
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>host</TITLE
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><META
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NAME="GENERATOR"
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CONTENT="Modular DocBook HTML Stylesheet Version 1.7"></HEAD
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><BODY
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CLASS="REFENTRY"
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BGCOLOR="#FFFFFF"
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TEXT="#000000"
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LINK="#0000FF"
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VLINK="#840084"
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ALINK="#0000FF"
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><H1
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><A
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NAME="AEN1"
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></A
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>host</H1
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><DIV
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CLASS="REFNAMEDIV"
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><A
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NAME="AEN8"
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></A
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><H2
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>Name</H2
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>host -- DNS lookup utility</DIV
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><DIV
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CLASS="REFSYNOPSISDIV"
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><A
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NAME="AEN11"
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></A
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><H2
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>Synopsis</H2
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><P
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><B
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CLASS="COMMAND"
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>host</B
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> [<VAR
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CLASS="OPTION"
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>-aCdlnrTwv</VAR
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>] [<VAR
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CLASS="OPTION"
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>-c <VAR
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CLASS="REPLACEABLE"
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>class</VAR
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></VAR
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>] [<VAR
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CLASS="OPTION"
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>-N <VAR
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CLASS="REPLACEABLE"
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>ndots</VAR
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></VAR
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>] [<VAR
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CLASS="OPTION"
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>-R <VAR
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CLASS="REPLACEABLE"
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>number</VAR
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></VAR
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>] [<VAR
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CLASS="OPTION"
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>-t <VAR
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CLASS="REPLACEABLE"
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>type</VAR
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></VAR
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>] [<VAR
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CLASS="OPTION"
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>-W <VAR
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CLASS="REPLACEABLE"
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>wait</VAR
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></VAR
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>] {name} [server]</P
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></DIV
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><DIV
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CLASS="REFSECT1"
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><A
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NAME="AEN33"
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></A
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><H2
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>DESCRIPTION</H2
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><P
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><B
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CLASS="COMMAND"
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>host</B
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>
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is a simple utility for performing DNS lookups.
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It is normally used to convert names to IP addresses and vice versa.
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When no arguments or options are given,
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<B
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CLASS="COMMAND"
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>host</B
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>
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prints a short summary of its command line arguments and options.</P
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><P
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><VAR
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CLASS="PARAMETER"
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>name</VAR
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> is the domain name that is to be looked
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up. It can also be a dotted-decimal IPv4 address or a colon-delimited
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IPv6 address, in which case <B
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CLASS="COMMAND"
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>host</B
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> will by default
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perform a reverse lookup for that address.
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<VAR
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CLASS="PARAMETER"
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>server</VAR
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> is an optional argument which is either
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the name or IP address of the name server that <B
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CLASS="COMMAND"
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>host</B
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>
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should query instead of the server or servers listed in
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<TT
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CLASS="FILENAME"
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>/etc/resolv.conf</TT
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>.</P
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><P
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>The <VAR
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CLASS="OPTION"
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>-a</VAR
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> (all) option is equivalent to setting the
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<VAR
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CLASS="OPTION"
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>-v</VAR
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> option and asking <B
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CLASS="COMMAND"
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>host</B
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> to make
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a query of type ANY.</P
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><P
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>When the <VAR
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CLASS="OPTION"
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>-C</VAR
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> option is used, <B
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CLASS="COMMAND"
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>host</B
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>
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will attempt to display the SOA records for zone
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<VAR
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CLASS="PARAMETER"
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>name</VAR
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> from all the listed authoritative name
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servers for that zone. The list of name servers is defined by the NS
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records that are found for the zone.</P
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><P
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>The <VAR
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CLASS="OPTION"
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>-c</VAR
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> option instructs to make a DNS query of class
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<VAR
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CLASS="PARAMETER"
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>class</VAR
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>. This can be used to lookup Hesiod or
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Chaosnet class resource records. The default class is IN (Internet).</P
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><P
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>Verbose output is generated by <B
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CLASS="COMMAND"
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>host</B
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> when the
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<VAR
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CLASS="OPTION"
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>-d</VAR
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> or <VAR
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CLASS="OPTION"
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>-v</VAR
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> option is used. The two
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options are equivalent. They have been provided for backwards
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compatibility. In previous versions, the <VAR
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CLASS="OPTION"
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>-d</VAR
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> option
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switched on debugging traces and <VAR
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CLASS="OPTION"
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>-v</VAR
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> enabled verbose
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output.</P
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><P
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>List mode is selected by the <VAR
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CLASS="OPTION"
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>-l</VAR
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> option. This makes
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<B
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CLASS="COMMAND"
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>host</B
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> perform a zone transfer for zone
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<VAR
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CLASS="PARAMETER"
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>name</VAR
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>. The argument is provided for
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compatibility with older implementations. This option is equivalent
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to making a query of type AXFR.</P
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><P
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>The <VAR
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CLASS="OPTION"
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>-n</VAR
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>
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option specifies that reverse lookups of IPv6 addresses should
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use the IP6.INT domain and "nibble" labels as defined in RFC1886.
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The default is to use IP6.ARPA and binary labels as defined in RFC2874.</P
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><P
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>The <VAR
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CLASS="OPTION"
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>-N</VAR
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> option sets the number of dots that have to be
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in <VAR
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CLASS="PARAMETER"
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>name</VAR
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> for it to be considered absolute. The
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default value is that defined using the ndots statement in
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<TT
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CLASS="FILENAME"
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>/etc/resolv.conf</TT
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>, or 1 if no ndots statement is
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present. Names with fewer dots are interpreted as relative names and
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will be searched for in the domains listed in the <SPAN
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CLASS="TYPE"
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>search</SPAN
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>
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or <SPAN
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CLASS="TYPE"
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>domain</SPAN
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> directive in
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<TT
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CLASS="FILENAME"
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>/etc/resolv.conf</TT
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>.</P
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><P
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>The number of UDP retries for a lookup can be changed with the
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<VAR
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CLASS="OPTION"
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>-R</VAR
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> option. <VAR
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CLASS="PARAMETER"
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>number</VAR
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> indicates
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how many times <B
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CLASS="COMMAND"
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>host</B
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> will repeat a query that does
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not get answered. The default number of retries is 1. If
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<VAR
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CLASS="PARAMETER"
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>number</VAR
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> is negative or zero, the number of
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retries will default to 1.</P
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><P
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>Non-recursive queries can be made via the <VAR
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CLASS="OPTION"
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>-r</VAR
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> option.
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Setting this option clears the <SPAN
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CLASS="TYPE"
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>RD</SPAN
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> — recursion
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desired — bit in the query which <B
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CLASS="COMMAND"
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>host</B
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> makes.
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This should mean that the name server receiving the query will not
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attempt to resolve <VAR
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CLASS="PARAMETER"
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>name</VAR
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>. The
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<VAR
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CLASS="OPTION"
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>-r</VAR
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> option enables <B
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CLASS="COMMAND"
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>host</B
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> to mimic
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the behaviour of a name server by making non-recursive queries and
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expecting to receive answers to those queries that are usually
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referrals to other name servers.</P
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><P
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>By default <B
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CLASS="COMMAND"
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>host</B
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> uses UDP when making queries. The
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<VAR
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CLASS="OPTION"
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>-T</VAR
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> option makes it use a TCP connection when querying
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the name server. TCP will be automatically selected for queries that
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require it, such as zone transfer (AXFR) requests.</P
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><P
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>The <VAR
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CLASS="OPTION"
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>-t</VAR
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> option is used to select the query type.
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<VAR
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CLASS="PARAMETER"
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>type</VAR
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> can be any recognised query type: CNAME,
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NS, SOA, SIG, KEY, AXFR, etc. When no query type is specified,
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<B
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CLASS="COMMAND"
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>host</B
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> automatically selects an appropriate query
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type. By default it looks for A records, but if the
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<VAR
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CLASS="OPTION"
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>-C</VAR
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> option was given, queries will be made for SOA
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records, and if <VAR
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CLASS="PARAMETER"
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>name</VAR
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> is a dotted-decimal IPv4
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address or colon-delimited IPv6 address, <B
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CLASS="COMMAND"
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>host</B
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> will
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query for PTR records.</P
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><P
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>The time to wait for a reply can be controlled through the
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<VAR
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CLASS="OPTION"
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>-W</VAR
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> and <VAR
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CLASS="OPTION"
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>-w</VAR
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> options. The
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<VAR
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CLASS="OPTION"
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>-W</VAR
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> option makes <B
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CLASS="COMMAND"
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>host</B
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> wait for
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<VAR
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CLASS="PARAMETER"
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>wait</VAR
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> seconds. If <VAR
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CLASS="PARAMETER"
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>wait</VAR
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>
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is less than one, the wait interval is set to one second. When the
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<VAR
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CLASS="OPTION"
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>-w</VAR
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> option is used, <B
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CLASS="COMMAND"
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>host</B
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> will
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effectively wait forever for a reply. The time to wait for a response
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will be set to the number of seconds given by the hardware's maximum
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value for an integer quantity.</P
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></DIV
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><DIV
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CLASS="REFSECT1"
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><A
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NAME="AEN105"
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></A
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><H2
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>FILES</H2
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><P
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><TT
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CLASS="FILENAME"
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>/etc/resolv.conf</TT
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></P
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></DIV
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><DIV
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CLASS="REFSECT1"
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><A
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NAME="AEN109"
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></A
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><H2
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>SEE ALSO</H2
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><P
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><SPAN
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CLASS="CITEREFENTRY"
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><SPAN
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CLASS="REFENTRYTITLE"
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>dig</SPAN
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>(1)</SPAN
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>,
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<SPAN
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CLASS="CITEREFENTRY"
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><SPAN
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CLASS="REFENTRYTITLE"
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>named</SPAN
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>(8)</SPAN
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>.</P
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></DIV
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></BODY
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></HTML
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>
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