265 lines
4.7 KiB
HTML
265 lines
4.7 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML
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><HEAD
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><TITLE
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>The BIND 9 Lightweight Resolver</TITLE
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><META
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NAME="GENERATOR"
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CONTENT="Modular DocBook HTML Stylesheet Version 1.7"><LINK
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REL="HOME"
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TITLE="BIND 9 Administrator Reference Manual"
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HREF="Bv9ARM.html"><LINK
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REL="PREVIOUS"
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TITLE="Advanced DNS Features"
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HREF="Bv9ARM.ch04.html"><LINK
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REL="NEXT"
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TITLE="BIND 9 Configuration Reference"
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HREF="Bv9ARM.ch06.html"></HEAD
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><BODY
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CLASS="chapter"
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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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CELLSPACING="0"
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><TR
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><TH
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COLSPAN="3"
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ALIGN="center"
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>BIND 9 Administrator Reference Manual</TH
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></TR
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><TR
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><TD
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WIDTH="10%"
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ALIGN="left"
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VALIGN="bottom"
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><A
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HREF="Bv9ARM.ch04.html"
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ACCESSKEY="P"
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>Prev</A
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></TD
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WIDTH="80%"
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VALIGN="bottom"
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><TD
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WIDTH="10%"
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ALIGN="right"
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VALIGN="bottom"
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><A
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HREF="Bv9ARM.ch06.html"
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ACCESSKEY="N"
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>Next</A
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></TD
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></TR
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></TABLE
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><HR
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ALIGN="LEFT"
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WIDTH="100%"></DIV
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><DIV
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CLASS="chapter"
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><H1
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><A
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NAME="ch05"
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></A
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>Chapter 5. The <ACRONYM
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CLASS="acronym"
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>BIND</ACRONYM
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> 9 Lightweight Resolver</H1
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><DIV
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CLASS="TOC"
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><DL
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><DT
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><B
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>Table of Contents</B
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></DT
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><DT
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>5.1. <A
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HREF="Bv9ARM.ch05.html#AEN1044"
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>The Lightweight Resolver Library</A
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></DT
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><DT
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>5.2. <A
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HREF="Bv9ARM.ch05.html#lwresd"
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>Running a Resolver Daemon</A
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></DT
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></DL
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></DIV
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><DIV
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CLASS="sect1"
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><H1
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CLASS="sect1"
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><A
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NAME="AEN1044"
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>5.1. The Lightweight Resolver Library</A
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></H1
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><P
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>Traditionally applications have been linked with a stub resolver
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library that sends recursive DNS queries to a local caching name
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server.</P
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><P
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>IPv6 once introduced new complexity into the resolution process,
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such as following A6 chains and DNAME records, and simultaneous
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lookup of IPv4 and IPv6 addresses. Though most of the complexity was
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then removed, these are hard or impossible
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to implement in a traditional stub resolver.</P
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><P
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>Instead, <ACRONYM
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CLASS="acronym"
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>BIND</ACRONYM
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> 9 provides resolution services to local clients
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using a combination of a lightweight resolver library and a resolver
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daemon process running on the local host. These communicate using
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a simple UDP-based protocol, the "lightweight resolver protocol"
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that is distinct from and simpler than the full DNS protocol.</P
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></DIV
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><DIV
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CLASS="sect1"
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><H1
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CLASS="sect1"
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><A
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NAME="lwresd"
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>5.2. Running a Resolver Daemon</A
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></H1
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><P
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>To use the lightweight resolver interface, the system must
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run the resolver daemon <B
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CLASS="command"
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>lwresd</B
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> or a local
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name server configured with a <B
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CLASS="command"
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>lwres</B
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> statement.</P
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><P
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>By default, applications using the lightweight resolver library will make
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UDP requests to the IPv4 loopback address (127.0.0.1) on port 921. The
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address can be overridden by <B
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CLASS="command"
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>lwserver</B
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> lines in
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<TT
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CLASS="filename"
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>/etc/resolv.conf</TT
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>.</P
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><P
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>The daemon currently only looks in the DNS, but in the future
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it may use other sources such as <TT
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CLASS="filename"
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>/etc/hosts</TT
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>,
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NIS, etc.</P
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><P
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>The <B
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CLASS="command"
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>lwresd</B
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> daemon is essentially a
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caching-only name server that responds to requests using the lightweight
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resolver protocol rather than the DNS protocol. Because it needs
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to run on each host, it is designed to require no or minimal configuration.
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Unless configured otherwise, it uses the name servers listed on
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<B
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CLASS="command"
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>nameserver</B
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> lines in <TT
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CLASS="filename"
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>/etc/resolv.conf</TT
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>
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as forwarders, but is also capable of doing the resolution autonomously if
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none are specified.</P
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><P
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>The <B
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CLASS="command"
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>lwresd</B
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> daemon may also be configured with a
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<TT
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CLASS="filename"
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>named.conf</TT
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> style configuration file, in
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<TT
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CLASS="filename"
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>/etc/lwresd.conf</TT
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> by default. A name server may also
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be configured to act as a lightweight resolver daemon using the
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<B
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CLASS="command"
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>lwres</B
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> statement in <TT
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CLASS="filename"
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>named.conf</TT
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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="NAVFOOTER"
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><HR
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ALIGN="LEFT"
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WIDTH="100%"><TABLE
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SUMMARY="Footer navigation table"
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><TR
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><TD
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WIDTH="33%"
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ALIGN="left"
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VALIGN="top"
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><A
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HREF="Bv9ARM.ch04.html"
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ACCESSKEY="P"
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>Prev</A
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></TD
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><TD
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WIDTH="34%"
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ALIGN="center"
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VALIGN="top"
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><A
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HREF="Bv9ARM.html"
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ACCESSKEY="H"
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>Home</A
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WIDTH="33%"
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ALIGN="right"
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VALIGN="top"
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><A
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HREF="Bv9ARM.ch06.html"
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ACCESSKEY="N"
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>Next</A
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></TR
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><TR
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><TD
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WIDTH="33%"
|
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ALIGN="left"
|
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VALIGN="top"
|
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>Advanced DNS Features</TD
|
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><TD
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WIDTH="34%"
|
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ALIGN="center"
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VALIGN="top"
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> </TD
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><TD
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WIDTH="33%"
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ALIGN="right"
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VALIGN="top"
|
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><ACRONYM
|
|
CLASS="acronym"
|
|
>BIND</ACRONYM
|
|
> 9 Configuration Reference</TD
|
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></TR
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></TABLE
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></DIV
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></BODY
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> |