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.\"
.\" Copyright 1998 by the Massachusetts Institute of Technology.
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.TH ARES_QUERY 3 "24 July 1998"
.SH NAME
ares_query \- Initiate a single-question DNS query
.SH SYNOPSIS
.nf
.B #include <ares.h>
.PP
.B typedef void (*ares_callback)(void *\fIarg\fP, int \fIstatus\fP,
.B	int \fItimeouts\fP, unsigned char *\fIabuf\fP, int \fIalen\fP)
.PP
.B void ares_query(ares_channel \fIchannel\fP, const char *\fIname\fP,
.B 	int \fIdnsclass\fP, int \fItype\fP, ares_callback \fIcallback\fP,
.B	void *\fIarg\fP)
.fi
.SH DESCRIPTION
The
.B ares_query
function initiates a single-question DNS query on the name service
channel identified by
.IR channel .
The parameter
.I name
gives the query name as a NUL-terminated C string of period-separated
labels optionally ending with a period; periods and backslashes within
a label must be escaped with a backslash.  The parameters
.I dnsclass
and
.I type
give the class and type of the query using the values defined in
.BR <arpa/nameser.h> .
When the query is complete or has failed, the ares library will invoke
.IR callback .
Completion or failure of the query may happen immediately, or may
happen during a later call to
.BR ares_process (3)
or
.BR ares_destroy (3).
.PP
The callback argument
.I arg
is copied from the
.B ares_query
argument
.IR arg .
The callback argument
.I status
indicates whether the query succeeded and, if not, how it failed.  It
may have any of the following values:
.TP 19
.B ARES_SUCCESS
The query completed successfully.
.TP 19
.B ARES_ENODATA
The query completed but contains no answers.
.TP 19
.B ARES_EFORMERR
The query completed but the server claims that the query was
malformatted.
.TP 19
.B ARES_ESERVFAIL
The query completed but the server claims to have experienced a
failure.  (This code can only occur if the
.B ARES_FLAG_NOCHECKRESP
flag was specified at channel initialization time; otherwise, such
responses are ignored at the
.BR ares_send (3)
level.)
.TP 19
.B ARES_ENOTFOUND
The query completed but the queried-for domain name was not found.
.TP 19
.B ARES_ENOTIMP
The query completed but the server does not implement the operation
requested by the query.  (This code can only occur if the
.B ARES_FLAG_NOCHECKRESP
flag was specified at channel initialization time; otherwise, such
responses are ignored at the
.BR ares_send (3)
level.)
.TP 19
.B ARES_EREFUSED
The query completed but the server refused the query.  (This code can
only occur if the
.B ARES_FLAG_NOCHECKRESP
flag was specified at channel initialization time; otherwise, such