/contrib/bind9/bin/dig/host.1

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  1. .\" Copyright (C) 2004, 2005, 2007-2009 Internet Systems Consortium, Inc. ("ISC")
  2. .\" Copyright (C) 2000-2002 Internet Software Consortium.
  3. .\"
  4. .\" Permission to use, copy, modify, and/or distribute this software for any
  5. .\" purpose with or without fee is hereby granted, provided that the above
  6. .\" copyright notice and this permission notice appear in all copies.
  7. .\"
  8. .\" THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
  9. .\" REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
  10. .\" AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
  11. .\" INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
  12. .\" LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
  13. .\" OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
  14. .\" PERFORMANCE OF THIS SOFTWARE.
  15. .\"
  16. .\" $Id$
  17. .\"
  18. .hy 0
  19. .ad l
  20. .\" Title: host
  21. .\" Author:
  22. .\" Generator: DocBook XSL Stylesheets v1.71.1 <http://docbook.sf.net/>
  23. .\" Date: Jun 30, 2000
  24. .\" Manual: BIND9
  25. .\" Source: BIND9
  26. .\"
  27. .TH "HOST" "1" "Jun 30, 2000" "BIND9" "BIND9"
  28. .\" disable hyphenation
  29. .nh
  30. .\" disable justification (adjust text to left margin only)
  31. .ad l
  32. .SH "NAME"
  33. host \- DNS lookup utility
  34. .SH "SYNOPSIS"
  35. .HP 5
  36. \fBhost\fR [\fB\-aCdlnrsTwv\fR] [\fB\-c\ \fR\fB\fIclass\fR\fR] [\fB\-N\ \fR\fB\fIndots\fR\fR] [\fB\-R\ \fR\fB\fInumber\fR\fR] [\fB\-t\ \fR\fB\fItype\fR\fR] [\fB\-W\ \fR\fB\fIwait\fR\fR] [\fB\-m\ \fR\fB\fIflag\fR\fR] [\fB\-4\fR] [\fB\-6\fR] {name} [server]
  37. .SH "DESCRIPTION"
  38. .PP
  39. \fBhost\fR
  40. is a simple utility for performing DNS lookups. It is normally used to convert names to IP addresses and vice versa. When no arguments or options are given,
  41. \fBhost\fR
  42. prints a short summary of its command line arguments and options.
  43. .PP
  44. \fIname\fR
  45. 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
  46. \fBhost\fR
  47. will by default perform a reverse lookup for that address.
  48. \fIserver\fR
  49. is an optional argument which is either the name or IP address of the name server that
  50. \fBhost\fR
  51. should query instead of the server or servers listed in
  52. \fI/etc/resolv.conf\fR.
  53. .PP
  54. The
  55. \fB\-a\fR
  56. (all) option is equivalent to setting the
  57. \fB\-v\fR
  58. option and asking
  59. \fBhost\fR
  60. to make a query of type ANY.
  61. .PP
  62. When the
  63. \fB\-C\fR
  64. option is used,
  65. \fBhost\fR
  66. will attempt to display the SOA records for zone
  67. \fIname\fR
  68. from all the listed authoritative name servers for that zone. The list of name servers is defined by the NS records that are found for the zone.
  69. .PP
  70. The
  71. \fB\-c\fR
  72. option instructs to make a DNS query of class
  73. \fIclass\fR. This can be used to lookup Hesiod or Chaosnet class resource records. The default class is IN (Internet).
  74. .PP
  75. Verbose output is generated by
  76. \fBhost\fR
  77. when the
  78. \fB\-d\fR
  79. or
  80. \fB\-v\fR
  81. option is used. The two options are equivalent. They have been provided for backwards compatibility. In previous versions, the
  82. \fB\-d\fR
  83. option switched on debugging traces and
  84. \fB\-v\fR
  85. enabled verbose output.
  86. .PP
  87. List mode is selected by the
  88. \fB\-l\fR
  89. option. This makes
  90. \fBhost\fR
  91. perform a zone transfer for zone
  92. \fIname\fR. Transfer the zone printing out the NS, PTR and address records (A/AAAA). If combined with
  93. \fB\-a\fR
  94. all records will be printed.
  95. .PP
  96. The
  97. \fB\-i\fR
  98. option specifies that reverse lookups of IPv6 addresses should use the IP6.INT domain as defined in RFC1886. The default is to use IP6.ARPA.
  99. .PP
  100. The
  101. \fB\-N\fR
  102. option sets the number of dots that have to be in
  103. \fIname\fR
  104. for it to be considered absolute. The default value is that defined using the ndots statement in
  105. \fI/etc/resolv.conf\fR, or 1 if no ndots statement is present. Names with fewer dots are interpreted as relative names and will be searched for in the domains listed in the
  106. \fBsearch\fR
  107. or
  108. \fBdomain\fR
  109. directive in
  110. \fI/etc/resolv.conf\fR.
  111. .PP
  112. The number of UDP retries for a lookup can be changed with the
  113. \fB\-R\fR
  114. option.
  115. \fInumber\fR
  116. indicates how many times
  117. \fBhost\fR
  118. will repeat a query that does not get answered. The default number of retries is 1. If
  119. \fInumber\fR
  120. is negative or zero, the number of retries will default to 1.
  121. .PP
  122. Non\-recursive queries can be made via the
  123. \fB\-r\fR
  124. option. Setting this option clears the
  125. \fBRD\fR
  126. \(em recursion desired \(em bit in the query which
  127. \fBhost\fR
  128. makes. This should mean that the name server receiving the query will not attempt to resolve
  129. \fIname\fR. The
  130. \fB\-r\fR
  131. option enables
  132. \fBhost\fR
  133. to mimic the behavior of a name server by making non\-recursive queries and expecting to receive answers to those queries that are usually referrals to other name servers.
  134. .PP
  135. By default,
  136. \fBhost\fR
  137. uses UDP when making queries. The
  138. \fB\-T\fR
  139. option makes it use a TCP connection when querying the name server. TCP will be automatically selected for queries that require it, such as zone transfer (AXFR) requests.
  140. .PP
  141. The
  142. \fB\-4\fR
  143. option forces
  144. \fBhost\fR
  145. to only use IPv4 query transport. The
  146. \fB\-6\fR
  147. option forces
  148. \fBhost\fR
  149. to only use IPv6 query transport.
  150. .PP
  151. The
  152. \fB\-t\fR
  153. option is used to select the query type.
  154. \fItype\fR
  155. can be any recognized query type: CNAME, NS, SOA, SIG, KEY, AXFR, etc. When no query type is specified,
  156. \fBhost\fR
  157. automatically selects an appropriate query type. By default, it looks for A, AAAA, and MX records, but if the
  158. \fB\-C\fR
  159. option was given, queries will be made for SOA records, and if
  160. \fIname\fR
  161. is a dotted\-decimal IPv4 address or colon\-delimited IPv6 address,
  162. \fBhost\fR
  163. will query for PTR records. If a query type of IXFR is chosen the starting serial number can be specified by appending an equal followed by the starting serial number (e.g. \-t IXFR=12345678).
  164. .PP
  165. The time to wait for a reply can be controlled through the
  166. \fB\-W\fR
  167. and
  168. \fB\-w\fR
  169. options. The
  170. \fB\-W\fR
  171. option makes
  172. \fBhost\fR
  173. wait for
  174. \fIwait\fR
  175. seconds. If
  176. \fIwait\fR
  177. is less than one, the wait interval is set to one second. When the
  178. \fB\-w\fR
  179. option is used,
  180. \fBhost\fR
  181. will effectively wait forever for a reply. The time to wait for a response will be set to the number of seconds given by the hardware's maximum value for an integer quantity.
  182. .PP
  183. The
  184. \fB\-s\fR
  185. option tells
  186. \fBhost\fR
  187. \fInot\fR
  188. to send the query to the next nameserver if any server responds with a SERVFAIL response, which is the reverse of normal stub resolver behavior.
  189. .PP
  190. The
  191. \fB\-m\fR
  192. can be used to set the memory usage debugging flags
  193. \fIrecord\fR,
  194. \fIusage\fR
  195. and
  196. \fItrace\fR.
  197. .SH "IDN SUPPORT"
  198. .PP
  199. If
  200. \fBhost\fR
  201. has been built with IDN (internationalized domain name) support, it can accept and display non\-ASCII domain names.
  202. \fBhost\fR
  203. appropriately converts character encoding of domain name before sending a request to DNS server or displaying a reply from the server. If you'd like to turn off the IDN support for some reason, defines the
  204. \fBIDN_DISABLE\fR
  205. environment variable. The IDN support is disabled if the variable is set when
  206. \fBhost\fR
  207. runs.
  208. .SH "FILES"
  209. .PP
  210. \fI/etc/resolv.conf\fR
  211. .SH "SEE ALSO"
  212. .PP
  213. \fBdig\fR(1),
  214. \fBnamed\fR(8).
  215. .SH "COPYRIGHT"
  216. Copyright \(co 2004, 2005, 2007\-2009 Internet Systems Consortium, Inc. ("ISC")
  217. .br
  218. Copyright \(co 2000\-2002 Internet Software Consortium.
  219. .br