244 lines
5.1 KiB
Groff
244 lines
5.1 KiB
Groff
.\" (c) Magerya Vitaly
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.\"
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.\" Copying and distribution of this file, with or without modification,
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.\" are permitted in any medium without royalty provided the copyright
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.\" notice and this notice are preserved. This file is offered as-is,
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.\" without any warranty.
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.Dd Aug 27, 2012
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.Dt LDNS-HOST 1
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.Os
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.Sh NAME
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.Nm ldns-host
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.Nd DNS lookup utility
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.Sh SYNOPSIS
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.Nm
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.Op Fl aCdilrsTvw46
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.Op Fl c Ar class
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.Op Fl N Ar ndots
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.Op Fl R Ar number
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.Op Fl t Ar type
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.Op Fl W Ar wait
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.Ar name
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.Op Ar server
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.Sh DESCRIPTION
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.Nm
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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.
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.Pp
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.Ar name
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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,
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in which case
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.Nm
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will by default perform a reverse lookup for that address.
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.Pp
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When
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.Ar name
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is not provided,
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.Nm
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prints a short summary of it's usage.
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.Pp
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.Ar server
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is an optional argument which is either a domain name or an IP
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address of the name server that
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.Nm
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should query instead of the server or servers listed in
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.Pa /etc/resolv.conf .
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When
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.Ar server
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is a domain name, system resolver is used to obtain it's address.
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.Pp
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Supported options:
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.Bl -tag -width indent
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.It Fl a
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Make a verbose query of type
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.Cm ANY .
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Equivalent to
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.Fl v Fl t Cm ANY .
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.It Fl C
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Query for
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.Cm SOA
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records for zone
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.Ar name
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from all of it's authoritative name servers. The list of name
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servers is obtained via
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.Cm NS
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query for
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.Ar name .
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.It Fl c Ar class
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Perform DNS query of class
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.Ar class .
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Recognized classes are
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.Cm IN Pq Internet ,
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.Cm CH Pq Chaosnet ,
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.Cm HS Pq Hesiod ,
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.Cm NONE ,
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.Cm ANY
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and
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.Cm CLASS Ns Ar N
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(where
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.Ar N
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is a number from 1 to 255). Default is
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.Cm IN .
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.It Fl d
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Produce verbose output. This is a synonym for
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.Fl v ,
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and is provided for backward compatibility.
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.It Fl i
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Use IP6.INT domain for reverse lookups of IPv6 addresses (as
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defined in RFC1886; note that RFC4159 deprecates IP6.INT).
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By default IP6.ARPA is used.
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.It Fl l
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List all
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.Cm NS, PTR, A
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and
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.Cm AAAA
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records in zone
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.Ar name
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by performing a zone transfer
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.Pq Cm AXFR .
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You can combine this option with
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.Fl a
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to print all records, or with
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.Fl t
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to only print specific ones.
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.It Fl N Ar ndots
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Consider names with at least this many dots as absolute. That
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is, try to resolve them directly before consulting
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.Ic domain
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or
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.Ic search
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options from
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.Pa /etc/resolv.conf .
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.It Fl r
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Perform non-recursive query to the name server by clearing RD
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.Pq Dq recursion desired
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bit of the query.
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.It Fl R Ar number
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Retry this many times when a query does not receive an answer
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in time. The default is 1 retry. If
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.Ar number
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is negative or zero, 1 is used instead.
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.It Fl s
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Report SERVFAIL responses as they are, do not ignore them.
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.It Fl T
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Query name server over TCP. By default UDP is used, except for
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.Cm AXFR
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and
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.Cm IXFR
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queries, which require TCP.
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.Nm
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will also retry UDP queries in TCP mode if the UDP response was
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truncated (i.e. had TC bit set).
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.It Fl t Ar type
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Perform DNS query of type
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.Ar type ,
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which can be any standard query type name
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.Pq Cm A , CNAME , MX , TXT , No etc ,
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a wildcard query
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.Pq Cm ANY ,
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or
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.Cm TYPE Ns Ar N ,
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where
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.Ar N
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is a number from 1 to 65535. For
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.Cm IXFR Pq incremental zone transfer
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queries the starting serial number can be specified by appending
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an equal sign followed by the number
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.Pq e.g. Fl t Cm IXFR Ns =12345678 .
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.Pp
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The default is to query for
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.Cm A , AAAA , No and Cm MX
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records, unless
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.Fl C
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or
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.Fl l
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options are given (in which case
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.Cm SOA
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or
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.Cm AXFR
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queries are made) or
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.Ar name
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is a valid IP address
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(in which case reverse lookup using
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.Cm PTR
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query is performed).
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.It Fl v
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Produce verbose output.
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.It Fl w
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Wait forever (or for a very long time) for response from the
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name server.
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.It Fl W Ar wait
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Wait this many seconds for a reply from name server before timing
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out. If
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.Ar wait
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is negative or zero, value of 1 is used. The default is to wait
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10 seconds for TCP connections, and 5 seconds for UDP (both are
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subject to retries, see option
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.Fl R ) .
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.It Fl 4
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Only use IPv4 transport.
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.It Fl 6
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Only use IPv6 transport.
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.El
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.Sh FILES
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.Pa /etc/resolv.conf
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.Sh SEE ALSO
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.Xr drill 1 ,
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.Xr resolv.conf 5
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.Sh COMPATIBILITY
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.Nm
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aims to be reasonably compatible with
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.Sq host
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utility from BIND9 distribution, both in supported options and
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in produced output. Here is a list of known notable differences:
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.Bl -bullet
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.It
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Debugging options
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.Pq Fl D No and Fl m
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are not supported.
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.It
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Query class
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.Cm CLASS0
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and type
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.Cm TYPE0
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are not supported.
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.It
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Backslashes in domain names are treated especially.
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.It
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The maximum of 255 retries (option
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.Fl R )
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are supported.
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.It
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Some resource records are formatted differently. For example,
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.Cm RRSIG
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and
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.Cm DNSKEY
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records are displayed without spaces in them.
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.It
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When parsing
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.Pa /etc/resolv.conf
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commands
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.Ic sortlist
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and
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.Ic options
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are ignored. When multiple
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.Ic search
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and/or
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.Ic domain
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commands are present,
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.Nm
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first uses the last
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.Ic domain
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command, and then all of
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.Ic search
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commands, while
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.Sq host
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from BIND9 uses whatever command was specified last.
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.It
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.Sq Pseudosection TSIG
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is missing from verbose packet output.
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.El
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.Sh AUTHORS
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.An Vitaly Magerya Aq magv@tx97.net
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