head 1.31; access; symbols netbsd-8-3-RELEASE:1.30 netbsd-9-4-RELEASE:1.30 netbsd-10-0-RELEASE:1.31 netbsd-10-0-RC6:1.31 netbsd-10-0-RC5:1.31 netbsd-10-0-RC4:1.31 netbsd-10-0-RC3:1.31 netbsd-10-0-RC2:1.31 netbsd-10-0-RC1:1.31 netbsd-10:1.31.0.6 netbsd-10-base:1.31 netbsd-9-3-RELEASE:1.30 cjep_sun2x-base1:1.31 cjep_sun2x:1.31.0.4 cjep_sun2x-base:1.31 cjep_staticlib_x-base1:1.31 netbsd-9-2-RELEASE:1.30 cjep_staticlib_x:1.31.0.2 cjep_staticlib_x-base:1.31 netbsd-9-1-RELEASE:1.30 phil-wifi-20200421:1.30 phil-wifi-20200411:1.30 is-mlppp:1.30.0.36 is-mlppp-base:1.30 phil-wifi-20200406:1.30 netbsd-8-2-RELEASE:1.30 netbsd-9-0-RELEASE:1.30 netbsd-9-0-RC2:1.30 netbsd-9-0-RC1:1.30 phil-wifi-20191119:1.30 netbsd-9:1.30.0.34 netbsd-9-base:1.30 phil-wifi-20190609:1.30 netbsd-8-1-RELEASE:1.30 netbsd-8-1-RC1:1.30 pgoyette-compat-merge-20190127:1.30 pgoyette-compat-20190127:1.30 pgoyette-compat-20190118:1.30 pgoyette-compat-1226:1.30 pgoyette-compat-1126:1.30 pgoyette-compat-1020:1.30 pgoyette-compat-0930:1.30 pgoyette-compat-0906:1.30 netbsd-7-2-RELEASE:1.30 pgoyette-compat-0728:1.30 netbsd-8-0-RELEASE:1.30 phil-wifi:1.30.0.32 phil-wifi-base:1.30 pgoyette-compat-0625:1.30 netbsd-8-0-RC2:1.30 pgoyette-compat-0521:1.30 pgoyette-compat-0502:1.30 pgoyette-compat-0422:1.30 netbsd-8-0-RC1:1.30 pgoyette-compat-0415:1.30 pgoyette-compat-0407:1.30 pgoyette-compat-0330:1.30 pgoyette-compat-0322:1.30 pgoyette-compat-0315:1.30 netbsd-7-1-2-RELEASE:1.30 pgoyette-compat:1.30.0.30 pgoyette-compat-base:1.30 netbsd-7-1-1-RELEASE:1.30 matt-nb8-mediatek:1.30.0.28 matt-nb8-mediatek-base:1.30 perseant-stdc-iso10646:1.30.0.26 perseant-stdc-iso10646-base:1.30 netbsd-8:1.30.0.24 netbsd-8-base:1.30 prg-localcount2-base3:1.30 prg-localcount2-base2:1.30 prg-localcount2-base1:1.30 prg-localcount2:1.30.0.22 prg-localcount2-base:1.30 pgoyette-localcount-20170426:1.30 bouyer-socketcan-base1:1.30 pgoyette-localcount-20170320:1.30 netbsd-7-1:1.30.0.20 netbsd-7-1-RELEASE:1.30 netbsd-7-1-RC2:1.30 netbsd-7-nhusb-base-20170116:1.30 bouyer-socketcan:1.30.0.18 bouyer-socketcan-base:1.30 pgoyette-localcount-20170107:1.30 netbsd-7-1-RC1:1.30 pgoyette-localcount-20161104:1.30 netbsd-7-0-2-RELEASE:1.30 localcount-20160914:1.30 netbsd-7-nhusb:1.30.0.16 netbsd-7-nhusb-base:1.30 pgoyette-localcount-20160806:1.30 pgoyette-localcount-20160726:1.30 pgoyette-localcount:1.30.0.14 pgoyette-localcount-base:1.30 netbsd-7-0-1-RELEASE:1.30 netbsd-7-0:1.30.0.12 netbsd-7-0-RELEASE:1.30 netbsd-7-0-RC3:1.30 netbsd-7-0-RC2:1.30 netbsd-7-0-RC1:1.30 netbsd-5-2-3-RELEASE:1.24 netbsd-5-1-5-RELEASE:1.24 netbsd-6-0-6-RELEASE:1.27 netbsd-6-1-5-RELEASE:1.27 netbsd-7:1.30.0.10 netbsd-7-base:1.30 yamt-pagecache-base9:1.30 yamt-pagecache-tag8:1.27.2.1 netbsd-6-1-4-RELEASE:1.27 netbsd-6-0-5-RELEASE:1.27 tls-earlyentropy:1.30.0.8 tls-earlyentropy-base:1.30 riastradh-xf86-video-intel-2-7-1-pre-2-21-15:1.30 riastradh-drm2-base3:1.30 netbsd-6-1-3-RELEASE:1.27 netbsd-6-0-4-RELEASE:1.27 netbsd-5-2-2-RELEASE:1.24 netbsd-5-1-4-RELEASE:1.24 netbsd-6-1-2-RELEASE:1.27 netbsd-6-0-3-RELEASE:1.27 netbsd-5-2-1-RELEASE:1.24 netbsd-5-1-3-RELEASE:1.24 netbsd-6-1-1-RELEASE:1.27 riastradh-drm2-base2:1.30 riastradh-drm2-base1:1.30 riastradh-drm2:1.30.0.4 riastradh-drm2-base:1.30 netbsd-6-1:1.27.0.10 netbsd-6-0-2-RELEASE:1.27 netbsd-6-1-RELEASE:1.27 netbsd-6-1-RC4:1.27 netbsd-6-1-RC3:1.27 agc-symver:1.30.0.6 agc-symver-base:1.30 netbsd-6-1-RC2:1.27 netbsd-6-1-RC1:1.27 yamt-pagecache-base8:1.30 netbsd-5-2:1.24.0.40 netbsd-6-0-1-RELEASE:1.27 yamt-pagecache-base7:1.30 netbsd-5-2-RELEASE:1.24 netbsd-5-2-RC1:1.24 matt-nb6-plus-nbase:1.27 yamt-pagecache-base6:1.30 netbsd-6-0:1.27.0.8 netbsd-6-0-RELEASE:1.27 netbsd-6-0-RC2:1.27 tls-maxphys:1.30.0.2 tls-maxphys-base:1.30 matt-nb6-plus:1.27.0.6 matt-nb6-plus-base:1.27 netbsd-6-0-RC1:1.27 yamt-pagecache-base5:1.27 yamt-pagecache-base4:1.27 netbsd-6:1.27.0.4 netbsd-6-base:1.27 netbsd-5-1-2-RELEASE:1.24 netbsd-5-1-1-RELEASE:1.24 yamt-pagecache-base3:1.27 yamt-pagecache-base2:1.27 yamt-pagecache:1.27.0.2 yamt-pagecache-base:1.27 cherry-xenmp:1.25.0.4 cherry-xenmp-base:1.25 bouyer-quota2-nbase:1.25 bouyer-quota2:1.25.0.2 bouyer-quota2-base:1.25 matt-mips64-premerge-20101231:1.25 matt-nb5-mips64-premerge-20101231:1.24 matt-nb5-pq3:1.24.0.38 matt-nb5-pq3-base:1.24 netbsd-5-1:1.24.0.36 netbsd-5-1-RELEASE:1.24 netbsd-5-1-RC4:1.24 matt-nb5-mips64-k15:1.24 netbsd-5-1-RC3:1.24 netbsd-5-1-RC2:1.24 netbsd-5-1-RC1:1.24 netbsd-5-0-2-RELEASE:1.24 matt-nb5-mips64-premerge-20091211:1.24 matt-premerge-20091211:1.24 matt-nb5-mips64-u2-k2-k4-k7-k8-k9:1.24 matt-nb4-mips64-k7-u2a-k9b:1.24 matt-nb5-mips64-u1-k1-k5:1.24 matt-nb5-mips64:1.24.0.34 netbsd-5-0-1-RELEASE:1.24 jym-xensuspend-nbase:1.24 netbsd-5-0:1.24.0.32 netbsd-5-0-RELEASE:1.24 netbsd-5-0-RC4:1.24 netbsd-5-0-RC3:1.24 netbsd-5-0-RC2:1.24 jym-xensuspend:1.24.0.30 jym-xensuspend-base:1.24 netbsd-5-0-RC1:1.24 netbsd-5:1.24.0.28 netbsd-5-base:1.24 matt-mips64-base2:1.24 matt-mips64:1.24.0.26 netbsd-4-0-1-RELEASE:1.24 wrstuden-revivesa-base-3:1.24 wrstuden-revivesa-base-2:1.24 wrstuden-fixsa-newbase:1.24 wrstuden-revivesa-base-1:1.24 yamt-pf42-base4:1.24 yamt-pf42-base3:1.24 hpcarm-cleanup-nbase:1.24 yamt-pf42-baseX:1.24 yamt-pf42-base2:1.24 wrstuden-revivesa:1.24.0.24 wrstuden-revivesa-base:1.24 yamt-pf42:1.24.0.22 yamt-pf42-base:1.24 mjf-devfs2:1.24.0.20 mjf-devfs2-base:1.24 keiichi-mipv6-nbase:1.24 keiichi-mipv6:1.24.0.18 keiichi-mipv6-base:1.24 matt-armv6-nbase:1.24 matt-armv6-prevmlocking:1.24 wrstuden-fixsa-base-1:1.24 netbsd-4-0:1.24.0.16 netbsd-4-0-RELEASE:1.24 cube-autoconf:1.24.0.14 cube-autoconf-base:1.24 netbsd-4-0-RC5:1.24 netbsd-4-0-RC4:1.24 netbsd-4-0-RC3:1.24 netbsd-4-0-RC2:1.24 netbsd-4-0-RC1:1.24 matt-armv6:1.24.0.12 matt-armv6-base:1.24 matt-mips64-base:1.24 hpcarm-cleanup:1.24.0.10 hpcarm-cleanup-base:1.24 netbsd-3-1-1-RELEASE:1.23 netbsd-3-0-3-RELEASE:1.23 wrstuden-fixsa:1.24.0.8 wrstuden-fixsa-base:1.24 abandoned-netbsd-4-base:1.24 abandoned-netbsd-4:1.24.0.4 netbsd-3-1:1.23.0.12 netbsd-3-1-RELEASE:1.23 netbsd-3-0-2-RELEASE:1.23 netbsd-3-1-RC4:1.23 netbsd-3-1-RC3:1.23 netbsd-3-1-RC2:1.23 netbsd-3-1-RC1:1.23 netbsd-4:1.24.0.6 netbsd-4-base:1.24 chap-midi-nbase:1.24 netbsd-3-0-1-RELEASE:1.23 chap-midi:1.24.0.2 chap-midi-base:1.24 netbsd-3-0:1.23.0.10 netbsd-3-0-RELEASE:1.23 netbsd-3-0-RC6:1.23 netbsd-3-0-RC5:1.23 netbsd-3-0-RC4:1.23 netbsd-3-0-RC3:1.23 netbsd-3-0-RC2:1.23 netbsd-3-0-RC1:1.23 netbsd-2-0-3-RELEASE:1.23 netbsd-2-1:1.23.0.8 netbsd-2-1-RELEASE:1.23 netbsd-2-1-RC6:1.23 netbsd-2-1-RC5:1.23 netbsd-2-1-RC4:1.23 netbsd-2-1-RC3:1.23 netbsd-2-1-RC2:1.23 netbsd-2-1-RC1:1.23 netbsd-2-0-2-RELEASE:1.23 netbsd-3:1.23.0.6 netbsd-3-base:1.23 netbsd-2-0-1-RELEASE:1.23 netbsd-2:1.23.0.4 netbsd-2-base:1.23 netbsd-2-0-RELEASE:1.23 netbsd-2-0-RC5:1.23 netbsd-2-0-RC4:1.23 netbsd-2-0-RC3:1.23 netbsd-2-0-RC2:1.23 netbsd-2-0-RC1:1.23 netbsd-2-0:1.23.0.2 netbsd-2-0-base:1.23 netbsd-1-6-PATCH002-RELEASE:1.21.2.1 netbsd-1-6-PATCH002:1.21.2.1 netbsd-1-6-PATCH002-RC4:1.21.2.1 netbsd-1-6-PATCH002-RC3:1.21.2.1 netbsd-1-6-PATCH002-RC2:1.21.2.1 netbsd-1-6-PATCH002-RC1:1.21.2.1 netbsd-1-6-PATCH001:1.21 netbsd-1-6-PATCH001-RELEASE:1.21 netbsd-1-6-PATCH001-RC3:1.21 netbsd-1-6-PATCH001-RC2:1.21 netbsd-1-6-PATCH001-RC1:1.21 fvdl_fs64_base:1.21 netbsd-1-6-RELEASE:1.21 netbsd-1-6-RC3:1.21 netbsd-1-6-RC2:1.21 netbsd-1-6-RC1:1.21 netbsd-1-6:1.21.0.2 netbsd-1-6-base:1.21 netbsd-1-5-PATCH003:1.16.2.1 netbsd-1-5-PATCH002:1.16 netbsd-1-5-PATCH001:1.16 netbsd-1-5-RELEASE:1.16 netbsd-1-5-BETA2:1.16 netbsd-1-5-BETA:1.16 netbsd-1-4-PATCH003:1.12 netbsd-1-5-ALPHA2:1.16 netbsd-1-5:1.16.0.2 netbsd-1-5-base:1.16 minoura-xpg4dl:1.14.0.2 minoura-xpg4dl-base:1.14 netbsd-1-4-PATCH002:1.12 wrstuden-devbsize-19991221:1.12 wrstuden-devbsize:1.12.0.6 wrstuden-devbsize-base:1.12 comdex-fall-1999:1.12.0.4 comdex-fall-1999-base:1.12 netbsd-1-4-PATCH001:1.12 netbsd-1-4-RELEASE:1.12 netbsd-1-4:1.12.0.2 netbsd-1-4-base:1.12 netbsd-1-3-PATCH003:1.9 netbsd-1-3-PATCH003-CANDIDATE2:1.9 netbsd-1-3-PATCH003-CANDIDATE1:1.9 netbsd-1-3-PATCH003-CANDIDATE0:1.9 netbsd-1-3-PATCH002:1.9 netbsd-1-3-PATCH001:1.9 netbsd-1-3-RELEASE:1.9 netbsd-1-3-BETA:1.9 netbsd-1-3:1.9.0.2 netbsd-1-3-base:1.9 lukem-nsswitch2:1.7.0.6 netbsd-1-2-PATCH001:1.7 nsswitch:1.7.0.2 netbsd-1-2-RELEASE:1.7 netbsd-1-2-BETA:1.7 netbsd-1-2:1.7.0.4 netbsd-1-2-base:1.7 netbsd-1-1-PATCH001:1.6 netbsd-1-1-RELEASE:1.6 netbsd-1-1:1.6.0.2 netbsd-1-1-base:1.6 netbsd-1-0-PATCH06:1.4 netbsd-1-0-PATCH05:1.4 netbsd-1-0-PATCH04:1.4 netbsd-1-0-PATCH03:1.4 netbsd-1-0-PATCH02:1.4 netbsd-1-0-PATCH1:1.4 netbsd-1-0-PATCH0:1.4 netbsd-1-0-RELEASE:1.4 netbsd-1-0:1.4.0.2 netbsd-1-0-base:1.4 netbsd-0-9-RELEASE:1.1.1.1 netbsd-0-9-BETA:1.1.1.1 netbsd-0-9-ALPHA2:1.1.1.1 netbsd-0-9-ALPHA:1.1.1.1 netbsd-0-9:1.1.1.1.0.2 netbsd-0-9-base:1.1.1.1 netbsd-0-8:1.1.1.1 netbsd-alpha-1:1.1.1.1 patchkit-0-2-2:1.1.1.1 WFJ-386bsd-01:1.1.1.1 WFJ-920714:1.1.1; locks; strict; comment @.\" @; 1.31 date 2021.04.30.16.12.18; author christos; state Exp; branches; next 1.30; commitid ODhRzLIfFmXBMkRC; 1.30 date 2012.09.09.18.09.24; author christos; state Exp; branches; next 1.29; 1.29 date 2012.09.09.17.11.23; author wiz; state Exp; branches; next 1.28; 1.28 date 2012.09.09.16.38.52; author christos; state Exp; branches; next 1.27; 1.27 date 2011.08.21.13.27.45; author wiz; state Exp; branches 1.27.2.1; next 1.26; 1.26 date 2011.08.21.11.04.21; author plunky; state Exp; branches; next 1.25; 1.25 date 2010.05.15.16.20.03; author jruoho; state Exp; branches; next 1.24; 1.24 date 2006.02.25.02.28.56; author wiz; state Exp; branches; next 1.23; 1.23 date 2003.09.07.16.22.29; author wiz; state Exp; branches; next 1.22; 1.22 date 2003.08.07.10.31.17; author agc; state Exp; branches; next 1.21; 1.21 date 2001.10.02.05.21.21; author itojun; state Exp; branches 1.21.2.1; next 1.20; 1.20 date 2001.09.14.06.30.56; author itojun; state Exp; branches; next 1.19; 1.19 date 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93.03.21.09.45.37; author cgd; state Exp; branches; next ; desc @@ 1.31 log @Mention that check-names is now the default. @ text @.\" $NetBSD: resolv.conf.5,v 1.30 2012/09/09 18:09:24 christos Exp $ .\" .\" Copyright (c) 1986, 1991 The Regents of the University of California. .\" All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" @@(#)resolver.5 5.12 (Berkeley) 5/10/91 .\" .Dd Arril 30, 2021 .Dt RESOLV.CONF 5 .Os .Sh NAME .Nm resolv.conf .Nd resolver configuration file .Sh DESCRIPTION The .Nm resolv.conf file specifies how the .Xr resolver 3 routines in the C library (which provide access to the Internet Domain Name System) should operate. The resolver configuration file contains information that is read by the resolver routines the first time they are invoked by a process. The file is designed to be human readable and contains a list of keywords with values that provide various types of resolver information. .Pp On a normally configured system this file should not be necessary. The only name server to be queried will be on the local machine, the domain name is determined from the host name, and the domain search path is constructed from the domain name. .Pp The different configuration options are: .Bl -tag -width nameserver .It Sy nameserver IPv4 address .Pq in dot notation or IPv6 address .Pq in hex-and-colon notation of a name server that the resolver should query. Scoped IPv6 address notation is accepted as well .Po see .Xr inet6 4 for details .Pc . Up to .Dv MAXNS (currently 3) name servers may be listed, one per keyword. If there are multiple servers, the resolver library queries them in the order listed. If no .Sy nameserver entries are present, the default is to use the name server on the local machine. (The algorithm used is to try a name server, and if the query times out, try the next, until out of name servers, then repeat trying all the name servers until a maximum number of retries are made). .It Sy domain Local domain name. Most queries for names within this domain can use short names relative to the local domain. If no .Sy domain entry is present, the domain is determined from the local host name returned by .Xr gethostname 3 ; the domain part is taken to be everything after the first .Sq \&. . Finally, if the host name does not contain a domain part, the root domain is assumed. .It Sy lookup This keyword is now ignored: its function has been superseded by features of .Xr nsswitch.conf 5 . .Pp .It Sy search Search list for host-name lookup. The search list is normally determined from the local domain name; by default, it begins with the local domain name, then successive parent domains that have at least two components in their names. This may be changed by listing the desired domain search path following the .Sy search keyword with spaces or tabs separating the names. Most resolver queries will be attempted using each component of the search path in turn until a match is found. Note that this process may be slow and will generate a lot of network traffic if the servers for the listed domains are not local, and that queries will time out if no server is available for one of the domains. .Pp The search list is currently limited to six domains with a total of 1024 characters. .It Sy sortlist Sortlist allows addresses returned by gethostbyname to be sorted. A sortlist is specified by IP address netmask pairs. The netmask is optional and defaults to the natural netmask of the net. The IP address and optional network pairs are separated by slashes. Up to 10 pairs may be specified, ie. .Pp .Sy sortlist 130.155.160.0/255.255.240.0 130.155.0.0 .It Sy options Options allows certain internal resolver variables to be modified. The syntax is: .Pp .Sy options option ... .Pp where option is one of the following: .Bl -tag -width no-check-names .It Sy debug enable debugging information, by setting RES_DEBUG in _res.options (see .Xr resolver 3 ) . .It Sy ndots:n sets a threshold for the number of dots which must appear in a name given to res_query (see .Xr resolver 3 ) before an initial absolute query will be made. The default for n is 1, meaning that if there are any dots in a name, the name will be tried first as an absolute name before any search list elements are appended to it. .It Sy timeout:n sets the amount of time the resolver will wait for a response from a remote name server before retrying the query via a different name server. Measured in seconds, the default is .Dv RES_TIMEOUT (see .Aq Pa resolv.h ) . .It Sy attempts:n sets the number of times the resolver will send a query to its name servers before giving up and returning an error to the calling application. The default is .Dv RES_DFLRETRY (see .Aq Pa resolv.h ) . .It Sy rotate sets .Dv RES_ROTATE in .Ft _res.options , which causes round robin selection of nameservers from among those listed. This has the effect of spreading the query load among all listed servers, rather than having all clients try the first listed server first every time. .It Sy no-check-names sets .Dv RES_NOCHECKNAME in .Ft _res.options , which disables the modern BIND checking of incoming host names and mail names for invalid characters such as underscore .Pq Sq _ , non-ASCII, or control characters. .It Sy check-names clears .Dv RES_NOCHECKNAME in .Ft _res.options , which enables the modern BIND checking of incoming host names and mail names as described above. This is the default. .It Sy edns0 attach OPT pseudo-RR for ENDS0 extension specified in RFC 2671, to inform DNS server of our receive buffer size. The option will allow DNS servers to take advantage of non-default receive buffer size, and to send larger replies. DNS query packets with EDNS0 extension is not compatible with non-EDNS0 DNS servers. The option must be used only when all the DNS servers listed in .Sy nameserver lines are able to handle EDNS0 extension. .It Sy inet6 enable support for IPv6-only applications, by setting RES_USE_INET6 in _res.options (see .Xr resolver 3 ) . The option is meaningful with certain kernel configuration only and use of this option is discouraged. .It Sy insecure1 Do not require IP source address on the reply packet to be equal to the servers' address. .It Sy insecure2 Do not check if the query section of the reply packet is equal to that of the query packet. For testing purposes only. .It Sy no-tld-query sets .Dv RES_NOTLDQUERY in .Ft _res.options . This option causes .Fn res_nsearch to not attempt to resolve a unqualified name as if it were a top level domain (TLD). This option can cause problems if the site has .Dq localhost as a TLD rather than having localhost on one or more elements of the search list. This option has no effect if neither .Dv RES_DEFNAMES or .Dv RES_DNSRCH is set. .El .El .Pp The .Sy domain and .Sy search keywords are mutually exclusive. If more than one instance of these keywords is present, the last instance will override. .Pp The .Sy search keyword of a system's .Pa resolv.conf file can be overridden on a per-process basis by setting the environment variable .Ev LOCALDOMAIN to a space-separated list of search domains. .Pp The .Sy options keyword of a system's .Pa resolv.conf file can be amended on a per-process basis by setting the environment variable .Ev RES_OPTIONS to a space-separated list of resolver options as explained above. .Pp The keyword and value must appear on a single line, and the keyword (e.g. .Sy nameserver ) must start the line. The value follows the keyword, separated by white space. .Sh FILES .Bl -tag -width /etc/resolv.conf -compact .It Pa /etc/resolv.conf The file .Nm resolv.conf resides in .Pa /etc . .El .Sh SEE ALSO .Xr gethostbyname 3 , .Xr resolver 3 , .Xr nsswitch.conf 5 , .Xr hostname 7 , .Xr named 8 , .Xr resolvconf 8 .Rs .%A Paul Vixie .%A Kevin J. Dunlap .%A Michael J. Karels .%T "Name Server Operations Guide for BIND" .%N Release 4.9.4 .%I CSRG , .%I Department of Electrical Engineering and Computer Sciences , .%I University of California, Berkeley .%D July 16, 1996 .%U http://www.dns.net/dnsrd/docs/bog/bog.html .Re .Sh HISTORY The .Nm resolv.conf file format appeared in .Bx 4.3 . @ 1.30 log @default to not checking host and mail names per rfc-2181 @ text @d1 1 a1 1 .\" $NetBSD: resolv.conf.5,v 1.29 2012/09/09 17:11:23 wiz Exp $ d32 1 a32 1 .Dd September 9, 2012 a181 1 This is the default. d189 1 @ 1.29 log @Whitespace and formatting cleanups. @ text @d1 1 a1 1 .\" $NetBSD: resolv.conf.5,v 1.28 2012/09/09 16:38:52 christos Exp $ d182 8 @ 1.28 log @document missing resolv.conf options @ text @d1 1 a1 1 .\" $NetBSD: resolv.conf.5,v 1.27 2011/08/21 13:27:45 wiz Exp $ d153 2 a154 2 name server before retrying the query via a different name server. Measured in seconds, the default is d157 1 a157 1 .Pa ) . d160 2 a161 2 before giving up and returning an error to the calling application. The default is d164 1 a164 1 .Pa ) . d179 3 a181 1 for invalid characters such as underscore (_), non-ASCII, or control characters. d212 1 a212 1 to not attempt to resolve a unqualified name as if it were a top level d214 3 a216 1 This option can cause problems if the site has "localhost" as a TLD rather d278 2 a279 2 .%I CSRG, .%I Department of Electrical Engineering and Computer Sciences, @ 1.27 log @New sentence, new line. @ text @d1 1 a1 1 .\" $NetBSD: resolv.conf.5,v 1.26 2011/08/21 11:04:21 plunky Exp $ d32 1 a32 1 .Dd August 21, 2010 d138 1 a138 1 .Bl -tag -width insecure1 d143 37 d203 16 a218 8 .It Sy ndots:n sets a threshold for the number of dots which must appear in a name given to res_query (see .Xr resolver 3 ) before an initial absolute query will be made. The default for n is 1, meaning that if there are any dots in a name, the name will be tried first as an absolute name before any search list elements are appended to it. @ 1.27.2.1 log @sync with head @ text @d1 1 a1 1 .\" $NetBSD: resolv.conf.5,v 1.27 2011/08/21 13:27:45 wiz Exp $ d32 1 a32 1 .Dd September 9, 2012 d138 1 a138 1 .Bl -tag -width no-check-names a142 47 .It Sy ndots:n sets a threshold for the number of dots which must appear in a name given to res_query (see .Xr resolver 3 ) before an initial absolute query will be made. The default for n is 1, meaning that if there are any dots in a name, the name will be tried first as an absolute name before any search list elements are appended to it. .It Sy timeout:n sets the amount of time the resolver will wait for a response from a remote name server before retrying the query via a different name server. Measured in seconds, the default is .Dv RES_TIMEOUT (see .Aq Pa resolv.h ) . .It Sy attempts:n sets the number of times the resolver will send a query to its name servers before giving up and returning an error to the calling application. The default is .Dv RES_DFLRETRY (see .Aq Pa resolv.h ) . .It Sy rotate sets .Dv RES_ROTATE in .Ft _res.options , which causes round robin selection of nameservers from among those listed. This has the effect of spreading the query load among all listed servers, rather than having all clients try the first listed server first every time. .It Sy no-check-names sets .Dv RES_NOCHECKNAME in .Ft _res.options , which disables the modern BIND checking of incoming host names and mail names for invalid characters such as underscore .Pq Sq _ , non-ASCII, or control characters. This is the default. .It Sy check-names clears .Dv RES_NOCHECKNAME in .Ft _res.options , which enables the modern BIND checking of incoming host names and mail names as described above. d166 8 a173 18 .It Sy no-tld-query sets .Dv RES_NOTLDQUERY in .Ft _res.options . This option causes .Fn res_nsearch to not attempt to resolve a unqualified name as if it were a top level domain (TLD). This option can cause problems if the site has .Dq localhost as a TLD rather than having localhost on one or more elements of the search list. This option has no effect if neither .Dv RES_DEFNAMES or .Dv RES_DNSRCH is set. d229 2 a230 2 .%I CSRG , .%I Department of Electrical Engineering and Computer Sciences , @ 1.26 log @SEE ALSO resolvconf(8) @ text @d1 1 a1 1 .\" $NetBSD: resolv.conf.5,v 1.25 2010/05/15 16:20:03 jruoho Exp $ d206 2 a207 2 must start the line. The value follows the keyword, separated by white space. @ 1.25 log @Complete the information in the reference (authors, publisher, date, URL). @ text @d1 1 a1 1 .\" $NetBSD: resolv.conf.5,v 1.24 2006/02/25 02:28:56 wiz Exp $ d32 1 a32 1 .Dd May 15, 2010 d221 2 a222 1 .Xr named 8 @ 1.24 log @Fix some typos. @ text @d1 1 a1 1 .\" $NetBSD: resolv.conf.5,v 1.23 2003/09/07 16:22:29 wiz Exp $ d32 1 a32 1 .Dd January 16, 1999 d92 2 a93 1 the domain part is taken to be everything after the first `.'. d223 3 d227 6 @ 1.23 log @Consistently use 'RFC 1234' instead of 'RFC1234' or 'RFC-1234'. From jmc@@openbsd. @ text @d1 1 a1 1 .\" $NetBSD: resolv.conf.5,v 1.22 2003/08/07 10:31:17 agc Exp $ d157 1 a157 1 use of this options is discouraged. @ 1.22 log @Move UCB-licensed code from 4-clause to 3-clause licence. Patches provided by Joel Baker in PR 22309, verified by myself. @ text @d1 1 a1 1 .\" $NetBSD: resolv.conf.5,v 1.21 2001/10/02 05:21:21 itojun Exp $ d143 1 a143 1 attach OPT pseudo-RR for ENDS0 extension specified in RFC2671, @ 1.21 log @typo @ text @d1 1 a1 1 .\" $NetBSD: resolv.conf.5,v 1.20 2001/09/14 06:30:56 itojun Exp $ d14 1 a14 5 .\" 3. All advertising materials mentioning features or use of this software .\" must display the following acknowledgement: .\" This product includes software developed by the University of .\" California, Berkeley and its contributors. .\" 4. Neither the name of the University nor the names of its contributors @ 1.21.2.1 log @Bring BIND up to 8.3.6 (requested by itojun in ticket #1536) @ text @d1 1 a1 1 .\" $NetBSD: resolv.conf.5,v 1.21 2001/10/02 05:21:21 itojun Exp $ d147 1 a147 1 attach OPT pseudo-RR for ENDS0 extension specified in RFC 2671, @ 1.20 log @adjust -width for .Bl @ text @d1 1 a1 1 .\" $NetBSD: resolv.conf.5,v 1.19 2001/09/13 11:07:48 itojun Exp $ d161 1 a161 1 use of this options is discourated. @ 1.19 log @document insecure[12]. @ text @d1 1 a1 1 .\" $NetBSD: resolv.conf.5,v 1.18 2001/09/08 01:29:08 wiz Exp $ d141 1 a141 1 .Bl -tag -width ndots:n @ 1.18 log @Whitespace/punctuation fixes. @ text @d1 1 a1 1 .\" $NetBSD: resolv.conf.5,v 1.17 2000/08/09 14:41:07 itojun Exp $ d162 7 @ 1.17 log @implement EDNS0 support, as EDNS0 support will be made mandatory for IPv6 transport-ready resolvers/DNS servers. need careful configuration when enable it. (default config is not affected). see manpage for details. XXX visible symbol __res_opt() is added, however, it is not supposed to be called from outside, libc minor is not bumped. @ text @d1 1 a1 1 .\" $NetBSD: resolv.conf.5,v 1.16 2000/06/15 10:28:50 itojun Exp $ d145 1 a145 1 .Xr resolver 3 ). d159 1 a159 1 .Xr resolver 3 ). @ 1.16 log @typo @ text @d1 1 a1 1 .\" $NetBSD: resolv.conf.5,v 1.15 2000/06/14 03:52:40 itojun Exp $ d146 10 @ 1.16.2.1 log @Pull up revision 1.21 (via patch, requested by itojun): Typo correction. @ text @d1 1 a1 1 .\" $NetBSD: resolv.conf.5,v 1.16 2000/06/15 10:28:50 itojun Exp $ d151 1 a151 1 use of this options is discouraged. @ 1.15 log @"nameserver" line happily accepts IPv6 numeric address. @ text @d1 1 a1 1 .\" $NetBSD: resolv.conf.5,v 1.14 2000/01/03 11:56:06 itojun Exp $ d67 1 a67 1 Scoped IPv6 address notation are accepted as well @ 1.14 log @clarify text for RES_USE_INET6. this is almost always unnecessary. @ text @d1 1 a1 1 .\" $NetBSD: resolv.conf.5,v 1.13 1999/12/28 02:40:38 mjl Exp $ d62 11 a72 2 Internet address (in dot notation) of a name server that the resolver should query. @ 1.14.2.1 log @Sync w/ netbsd-1-5-base. @ text @d1 1 a1 1 .\" $NetBSD: resolv.conf.5,v 1.16 2000/06/15 10:28:50 itojun Exp $ d62 2 a63 11 IPv4 address .Pq in dot notation or IPv6 address .Pq in hex-and-colon notation of a name server that the resolver should query. Scoped IPv6 address notation is accepted as well .Po see .Xr inet6 4 for details .Pc . @ 1.13 log @Fix spelling of separate. @ text @d1 1 a1 1 .\" $NetBSD: resolv.conf.5,v 1.12 1999/03/30 09:01:58 ross Exp $ d138 1 a138 1 enable support for IPv6 addresses, by setting RES_USE_INET6 in d141 2 @ 1.12 log @To say `deprecated' is to say that `lookup file bind' still works, but is discouraged and may someday be replaced. Instead, use words like `ignored' and `superseded', which describe the true situation. @ text @d1 1 a1 1 .\" $NetBSD: resolv.conf.5,v 1.11 1999/03/17 20:19:48 garbled Exp $ d120 1 a120 1 The IP address and optional network pairs are seperated by @ 1.11 log @More and more .Os cleanups. .Os is defined in the tmac.doc-common file, so we shouldn't override it with versions in the manpages. Many more to come. @ text @d1 1 a1 1 .\" $NetBSD: resolv.conf.5,v 1.10 1999/01/15 13:04:10 lukem Exp $ d91 2 a92 1 This keyword has been deprecated by the functionality described in @ 1.10 log @merge nsswitch into main branch @ text @d1 1 a1 1 .\" $NetBSD: resolv.conf.5,v 1.9 1997/07/14 01:49:25 mikel Exp $ d38 1 a38 1 .Os BSD 4 @ 1.9 log @xref gethostname(3) not obsolete gethostname(2) @ text @d1 1 a1 1 .\" $NetBSD: resolv.conf.5,v 1.8 1997/06/08 06:00:06 lukem Exp $ d36 1 a36 1 .Dd May 10, 1991 d91 2 a92 30 This keyword is used by the library routines .Xr gethostbyname 3 and .Xr gethostbyaddr 3 . It specifies which databases should be searched, and the order to do so. The legal space-separated values are .Bl -tag -width bind .It Sy bind use the Domain Name server by querying the .Xr named 8 .It Sy file search for entries in .Nm /etc/hosts .It Sy yp talk to the YP system if .Xr ypbind 8 is running .El .Pp If the .Sy lookup keyword is not used in the system's .Pa resolv.conf file then the assumed order is .Sy bind file . Furthermore, if the system's .Pa resolv.conf file does not exist, then the only database used is .Sy file . d193 1 @ 1.8 log @document "options inet6" @ text @d1 1 a1 1 .\" $NetBSD: resolv.conf.5,v 1.7 1996/03/06 18:22:16 scottr Exp $ d86 1 a86 1 .Xr gethostname 2 ; @ 1.7 log @Update search list length limit to match reality. @ text @d1 1 a1 1 .\" $NetBSD: resolv.conf.5,v 1.6 1994/12/12 06:13:29 deraadt Exp $ d161 7 a167 1 sets RES_DEBUG in _res.options. @ 1.7.6.1 log @* Add nsswitch.conf(5) * Document that resolv.conf's "lookup" keyword has been deprecated in favour of nsswitch.conf @ text @d1 1 a1 1 .\" $NetBSD: resolv.conf.5,v 1.7 1996/03/06 18:22:16 scottr Exp $ d36 1 a36 1 .Dd May 24, 1997 d91 30 a120 2 This keyword has been deprecated by the functionality described in .Xr nsswitch.conf 5 . a214 1 .Xr nsswitch.conf 5 , @ 1.7.6.2 log @sync with current @ text @d1 1 a1 1 .\" $NetBSD: resolv.conf.5,v 1.7.6.1 1997/05/23 20:16:28 lukem Exp $ d36 1 a36 1 .Dd January 14, 1999 d86 1 a86 1 .Xr gethostname 3 ; d133 1 a133 7 enable debugging information, by setting RES_DEBUG in _res.options (see .Xr resolver 3 ). .It Sy inet6 enable support for IPv6 addresses, by setting RES_USE_INET6 in _res.options (see .Xr resolver 3 ). @ 1.7.6.3 log @fix date @ text @d1 1 a1 1 .\" $NetBSD: resolv.conf.5,v 1.7.6.2 1999/01/14 08:27:48 lukem Exp $ d36 1 a36 1 .Dd January 16, 1999 @ 1.6 log @touchup @ text @d1 1 a1 1 .\" $NetBSD: resolv.conf.5,v 1.5 1994/11/30 19:31:29 jtc Exp $ d140 1 a140 1 with a total of 256 characters. @ 1.5 log @Merged with 4.4lite. Changed to conform to NetBSD's new RCS Id conventions. @ text @d1 1 a1 1 .\" $NetBSD: $ d97 1 a97 1 The legal space-seperated values are d102 3 a108 3 .It Sy file search for entries in .Nm /etc/hosts @ 1.4 log @document new resolver features: sortlist & options @ text @d1 2 d34 1 a34 2 .\" from: @@(#)resolver.5 5.12 (Berkeley) 5/10/91 .\" $Id: resolv.conf.5,v 1.3 1994/01/26 10:57:32 deraadt Exp $ @ 1.3 log @rename resolver(5) to resolv.conf(5) document new "lookup" keyword for gethostbyname()/gethostbyaddr() @ text @d33 1 a33 1 .\" $Id: resolver.5,v 1.2 1993/08/01 07:35:21 mycroft Exp $ d112 3 a114 3 keyword is not used in .Nm /etc/resolv.conf then the assumed order is d116 2 a117 2 Furthermore, if the file .Nm /etc/resolv.conf d140 30 d179 18 @ 1.2 log @Add RCS indentifiers. @ text @d33 1 a33 1 .\" $Id: $ d36 1 a36 1 .Dt RESOLVER 5 d39 1 a39 1 .Nm resolver a40 2 .Sh SYNOPSIS .Nm resolv.conf d43 2 d46 2 a47 2 is a set of routines in the C library which provide access to the Internet Domain Name System. d89 32 @ 1.1 log @Initial revision @ text @d32 2 a33 1 .\" @@(#)resolver.5 5.12 (Berkeley) 5/10/91 @ 1.1.1.1 log @initial import of 386bsd-0.1 sources @ text @@