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https://github.com/isc-projects/bind9.git
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529 lines
7.5 KiB
HTML
529 lines
7.5 KiB
HTML
<!--
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- Copyright (C) 2000, 2001 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 INTERNET SOFTWARE CONSORTIUM
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- DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
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- IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
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- INTERNET SOFTWARE CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT,
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- INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
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- FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
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- NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
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- WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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-->
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<HTML
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><HEAD
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><TITLE
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>lwres_getipnode</TITLE
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><META
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NAME="GENERATOR"
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CONTENT="Modular DocBook HTML Stylesheet Version 1.73
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"></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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>lwres_getipnode</A
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></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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>lwres_getipnodebyname, lwres_getipnodebyaddr, lwres_freehostent -- lightweight resolver nodename / address translation API</DIV
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><DIV
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CLASS="REFSYNOPSISDIV"
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><A
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NAME="AEN13"
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></A
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><H2
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>Synopsis</H2
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><DIV
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CLASS="FUNCSYNOPSIS"
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><A
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NAME="AEN14"
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></A
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><P
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></P
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><PRE
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CLASS="FUNCSYNOPSISINFO"
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>#include <lwres/netdb.h></PRE
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><P
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><CODE
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><CODE
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CLASS="FUNCDEF"
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>struct hostent *
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lwres_getipnodebyname</CODE
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>(const char *name, int af, int flags, int *error_num);</CODE
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></P
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><P
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><CODE
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><CODE
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CLASS="FUNCDEF"
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>struct hostent *
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lwres_getipnodebyaddr</CODE
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>(const void *src, size_t len, int af, int *error_num);</CODE
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></P
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><P
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><CODE
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><CODE
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CLASS="FUNCDEF"
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>void
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lwres_freehostent</CODE
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>(struct hostent *he);</CODE
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></P
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><P
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></P
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></DIV
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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="AEN34"
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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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>These functions perform thread safe, protocol independent
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nodename-to-address and address-to-nodename
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translation as defined in RFC2553.</P
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><P
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>They use a
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<SPAN
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CLASS="TYPE"
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>struct hostent</SPAN
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>
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which is defined in
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<TT
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CLASS="FILENAME"
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>namedb.h</TT
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>:
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<PRE
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CLASS="PROGRAMLISTING"
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>struct hostent {
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char *h_name; /* official name of host */
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char **h_aliases; /* alias list */
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int h_addrtype; /* host address type */
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int h_length; /* length of address */
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char **h_addr_list; /* list of addresses from name server */
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};
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#define h_addr h_addr_list[0] /* address, for backward compatibility */</PRE
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></P
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><P
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>The members of this structure are:
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<P
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></P
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><DIV
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CLASS="VARIABLELIST"
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><DL
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><DT
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><TT
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CLASS="CONSTANT"
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>h_name</TT
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></DT
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><DD
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><P
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>The official (canonical) name of the host.</P
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></DD
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><DT
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><TT
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CLASS="CONSTANT"
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>h_aliases</TT
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></DT
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><DD
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><P
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>A NULL-terminated array of alternate names (nicknames) for the host.</P
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></DD
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><DT
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><TT
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CLASS="CONSTANT"
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>h_addrtype</TT
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></DT
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><DD
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><P
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>The type of address being returned - usually
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<SPAN
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CLASS="TYPE"
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>PF_INET</SPAN
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>
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or
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<SPAN
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CLASS="TYPE"
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>PF_INET6</SPAN
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>. </P
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></DD
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><DT
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><TT
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CLASS="CONSTANT"
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>h_length</TT
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></DT
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><DD
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><P
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>The length of the address in bytes.</P
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></DD
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><DT
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><TT
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CLASS="CONSTANT"
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>h_addr_list</TT
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></DT
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><DD
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><P
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>A
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<SPAN
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CLASS="TYPE"
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>NULL</SPAN
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>
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terminated array of network addresses for the host.
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Host addresses are returned in network byte order.</P
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></DD
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></DL
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></DIV
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></P
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><P
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><TT
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CLASS="FUNCTION"
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>lwres_getipnodebyname()</TT
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>
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looks up addresses of protocol family
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<TT
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CLASS="PARAMETER"
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><I
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>af</I
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></TT
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>
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for the hostname
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<TT
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CLASS="PARAMETER"
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><I
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>name</I
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></TT
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>.
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The
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<TT
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CLASS="PARAMETER"
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><I
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>flags</I
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></TT
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>
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parameter contains ORed flag bits to
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specify the types of addresses that are searched
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for, and the types of addresses that are returned.
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The flag bits are:
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<P
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></P
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><DIV
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CLASS="VARIABLELIST"
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><DL
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><DT
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><TT
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CLASS="CONSTANT"
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>AI_V4MAPPED</TT
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></DT
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><DD
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><P
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>This is used with an
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<TT
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CLASS="PARAMETER"
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><I
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>af</I
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></TT
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>
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of AF_INET6, and causes IPv4 addresses to be returned as IPv4-mapped
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IPv6 addresses.</P
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></DD
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><DT
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><TT
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CLASS="CONSTANT"
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>AI_ALL</TT
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></DT
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><DD
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><P
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>This is used with an
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<TT
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CLASS="PARAMETER"
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><I
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>af</I
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></TT
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>
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of AF_INET6, and causes all known addresses (IPv6 and IPv4) to be returned.
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If AI_V4MAPPED is also set, the IPv4 addresses are return as mapped
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IPv6 addresses.</P
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></DD
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><DT
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><TT
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CLASS="CONSTANT"
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>AI_ADDRCONFIG</TT
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></DT
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><DD
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><P
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>Only return an IPv6 or IPv4 address if here is an active network
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interface of that type. This is not currently implemented
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in the BIND 9 lightweight resolver, and the flag is ignored.</P
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></DD
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><DT
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><TT
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CLASS="CONSTANT"
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>AI_DEFAULT</TT
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></DT
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><DD
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><P
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>This default sets the
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<TT
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CLASS="CONSTANT"
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>AI_V4MAPPED</TT
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>
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and
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<TT
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CLASS="CONSTANT"
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>AI_ADDRCONFIG</TT
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>
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flag bits.</P
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></DD
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></DL
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></DIV
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></P
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><P
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><TT
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CLASS="FUNCTION"
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>lwres_getipnodebyaddr()</TT
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>
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performs a reverse lookup
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of address
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<TT
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CLASS="PARAMETER"
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><I
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>src</I
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></TT
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>
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which is
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<TT
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CLASS="PARAMETER"
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><I
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>len</I
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></TT
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>
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bytes long.
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<TT
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CLASS="PARAMETER"
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><I
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>af</I
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></TT
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>
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denotes the protocol family, typically
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<SPAN
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CLASS="TYPE"
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>PF_INET</SPAN
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>
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or
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<SPAN
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CLASS="TYPE"
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>PF_INET6</SPAN
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>. </P
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><P
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><TT
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CLASS="FUNCTION"
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>lwres_freehostent()</TT
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>
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releases all the memory associated with
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the
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<SPAN
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CLASS="TYPE"
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>struct hostent</SPAN
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>
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pointer
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<TT
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CLASS="PARAMETER"
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><I
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>he</I
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></TT
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>.
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Any memory allocated for the
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<TT
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CLASS="CONSTANT"
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>h_name</TT
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>,
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<TT
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CLASS="CONSTANT"
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>h_addr_list</TT
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>
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and
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<TT
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CLASS="CONSTANT"
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>h_aliases</TT
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>
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is freed, as is the memory for the
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<SPAN
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CLASS="TYPE"
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>hostent</SPAN
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>
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structure itself.</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="AEN116"
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></A
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><H2
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>RETURN VALUES</H2
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><P
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>If an error occurs,
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<TT
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CLASS="FUNCTION"
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>lwres_getipnodebyname()</TT
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>
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and
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<TT
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CLASS="FUNCTION"
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>lwres_getipnodebyaddr()</TT
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>
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set
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<TT
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CLASS="PARAMETER"
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><I
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>*error_num</I
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></TT
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>
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to an appropriate error code and the function returns a
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<SPAN
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CLASS="TYPE"
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>NULL</SPAN
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>
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pointer.
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The error codes and their meanings are defined in
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<TT
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CLASS="FILENAME"
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><lwres/netdb.h></TT
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>:
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<P
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></P
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><DIV
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CLASS="VARIABLELIST"
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><DL
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><DT
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><TT
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CLASS="CONSTANT"
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>HOST_NOT_FOUND</TT
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></DT
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><DD
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><P
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>No such host is known.</P
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></DD
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><DT
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><TT
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CLASS="CONSTANT"
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>NO_ADDRESS</TT
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></DT
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><DD
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><P
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>The server recognised the request and the name but no address is
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available. Another type of request to the name server for the
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domain might return an answer.</P
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></DD
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><DT
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><TT
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CLASS="CONSTANT"
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>TRY_AGAIN</TT
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></DT
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><DD
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><P
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>A temporary and possibly transient error occurred, such as a
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failure of a server to respond. The request may succeed if
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retried.</P
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></DD
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><DT
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><TT
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CLASS="CONSTANT"
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>NO_RECOVERY</TT
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></DT
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><DD
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><P
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>An unexpected failure occurred, and retrying the request
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is pointless.</P
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></DD
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></DL
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></DIV
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></P
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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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>lwres_hstrerror</SPAN
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>(3)</SPAN
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>
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translates these error codes to suitable error messages.</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="AEN149"
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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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>RFC2553</SPAN
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></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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>lwres</SPAN
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>(3)</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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>lwres_gethostent</SPAN
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>(3)</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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>lwres_getaddrinfo</SPAN
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>(3)</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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>lwres_getnameinfo</SPAN
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>(3)</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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>lwres_hstrerror</SPAN
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>(3)</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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