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