1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
|
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<HTML
><HEAD
><TITLE
>The BIND 9 Lightweight Resolver</TITLE
><META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.7"><LINK
REL="HOME"
TITLE="BIND 9 Administrator Reference Manual"
HREF="Bv9ARM.html"><LINK
REL="PREVIOUS"
TITLE="Advanced DNS Features"
HREF="Bv9ARM.ch04.html"><LINK
REL="NEXT"
TITLE="BIND 9 Configuration Reference"
HREF="Bv9ARM.ch06.html"></HEAD
><BODY
CLASS="chapter"
BGCOLOR="#FFFFFF"
TEXT="#000000"
LINK="#0000FF"
VLINK="#840084"
ALINK="#0000FF"
><DIV
CLASS="NAVHEADER"
><TABLE
SUMMARY="Header navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TH
COLSPAN="3"
ALIGN="center"
>BIND 9 Administrator Reference Manual</TH
></TR
><TR
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="bottom"
><A
HREF="Bv9ARM.ch04.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="80%"
ALIGN="center"
VALIGN="bottom"
></TD
><TD
WIDTH="10%"
ALIGN="right"
VALIGN="bottom"
><A
HREF="Bv9ARM.ch06.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
></TABLE
><HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><DIV
CLASS="chapter"
><H1
><A
NAME="ch05"
></A
>Chapter 5. The <ACRONYM
CLASS="acronym"
>BIND</ACRONYM
> 9 Lightweight Resolver</H1
><DIV
CLASS="TOC"
><DL
><DT
><B
>Table of Contents</B
></DT
><DT
>5.1. <A
HREF="Bv9ARM.ch05.html#AEN1044"
>The Lightweight Resolver Library</A
></DT
><DT
>5.2. <A
HREF="Bv9ARM.ch05.html#lwresd"
>Running a Resolver Daemon</A
></DT
></DL
></DIV
><DIV
CLASS="sect1"
><H1
CLASS="sect1"
><A
NAME="AEN1044"
>5.1. The Lightweight Resolver Library</A
></H1
><P
>Traditionally applications have been linked with a stub resolver
library that sends recursive DNS queries to a local caching name
server.</P
><P
>IPv6 once introduced new complexity into the resolution process,
such as following A6 chains and DNAME records, and simultaneous
lookup of IPv4 and IPv6 addresses. Though most of the complexity was
then removed, these are hard or impossible
to implement in a traditional stub resolver.</P
><P
>Instead, <ACRONYM
CLASS="acronym"
>BIND</ACRONYM
> 9 provides resolution services to local clients
using a combination of a lightweight resolver library and a resolver
daemon process running on the local host. These communicate using
a simple UDP-based protocol, the "lightweight resolver protocol"
that is distinct from and simpler than the full DNS protocol.</P
></DIV
><DIV
CLASS="sect1"
><H1
CLASS="sect1"
><A
NAME="lwresd"
>5.2. Running a Resolver Daemon</A
></H1
><P
>To use the lightweight resolver interface, the system must
run the resolver daemon <B
CLASS="command"
>lwresd</B
> or a local
name server configured with a <B
CLASS="command"
>lwres</B
> statement.</P
><P
>By default, applications using the lightweight resolver library will make
UDP requests to the IPv4 loopback address (127.0.0.1) on port 921. The
address can be overridden by <B
CLASS="command"
>lwserver</B
> lines in
<TT
CLASS="filename"
>/etc/resolv.conf</TT
>.</P
><P
>The daemon currently only looks in the DNS, but in the future
it may use other sources such as <TT
CLASS="filename"
>/etc/hosts</TT
>,
NIS, etc.</P
><P
>The <B
CLASS="command"
>lwresd</B
> daemon is essentially a
caching-only name server that responds to requests using the lightweight
resolver protocol rather than the DNS protocol. Because it needs
to run on each host, it is designed to require no or minimal configuration.
Unless configured otherwise, it uses the name servers listed on
<B
CLASS="command"
>nameserver</B
> lines in <TT
CLASS="filename"
>/etc/resolv.conf</TT
>
as forwarders, but is also capable of doing the resolution autonomously if
none are specified.</P
><P
>The <B
CLASS="command"
>lwresd</B
> daemon may also be configured with a
<TT
CLASS="filename"
>named.conf</TT
> style configuration file, in
<TT
CLASS="filename"
>/etc/lwresd.conf</TT
> by default. A name server may also
be configured to act as a lightweight resolver daemon using the
<B
CLASS="command"
>lwres</B
> statement in <TT
CLASS="filename"
>named.conf</TT
>.</P
></DIV
></DIV
><DIV
CLASS="NAVFOOTER"
><HR
ALIGN="LEFT"
WIDTH="100%"><TABLE
SUMMARY="Footer navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
><A
HREF="Bv9ARM.ch04.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="Bv9ARM.html"
ACCESSKEY="H"
>Home</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
><A
HREF="Bv9ARM.ch06.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
>Advanced DNS Features</TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
> </TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
><ACRONYM
CLASS="acronym"
>BIND</ACRONYM
> 9 Configuration Reference</TD
></TR
></TABLE
></DIV
></BODY
></HTML
>
|
