147 lines
7.0 KiB
HTML
147 lines
7.0 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
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<!--Converted with LaTeX2HTML 96.1-c (Feb 29, 1996) by Nikos Drakos (nikos@cbl.leeds.ac.uk), CBLU, University of Leeds -->
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<HTML>
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<HEAD>
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<TITLE>The named.boot File</TITLE>
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</HEAD>
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<BODY LANG="EN">
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<A HREF="node1.html"><IMG WIDTH=65 HEIGHT=24 ALIGN=BOTTOM ALT="contents" SRC="contents_motif.gif"></A> <BR>
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<B> Next:</B> <A HREF="node88.html">The DNS Database Files</A>
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<B>Up:</B> <A HREF="node86.html">Running named</A>
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<B> Previous:</B> <A HREF="node86.html">Running named</A>
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<BR> <P>
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<H2><A NAME="SECTION008210000">The named.boot File</A></H2>
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<P>
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The named.boot file is generally very small and contains little
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else but pointers to master files containing zone information, and
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pointers to other name servers. Comments in the boot file start with a
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semicolon and extend to the next newline.
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Before we discuss the format of named.boot in more detail, we
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will take a look at the sample file for vlager given in
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figure-<A HREF="node87.html#resolvfignamedboot"><IMG ALIGN=BOTTOM ALT="gif" SRC="cross_ref_motif.gif"></A>.<A HREF="footnode.html#3691"><IMG ALIGN=BOTTOM ALT="gif" SRC="foot_motif.gif"></A>
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<P>
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<P><A NAME="3692"></A><BR>
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<STRONG>Figure:</STRONG>
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<A NAME="resolvfignamedboot"></A>
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The named.boot file for vlager.
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<pre>
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;
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; /etc/named.boot file for vlager.vbrew.com
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;
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directory /var/named
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;
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; domain file
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;---------------------------------------------------
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cache . named.ca
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primary vbrew.com named.hosts
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primary 0.0.127.in-addr.arpa named.local
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primary 72.191.in-addr.arpa named.rev
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</pre>
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<P>
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The cache and primary commands shown in this
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example load information into named. This information is taken
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from the master files specified in the second argument. They contain
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textual representations of DNS resource records, which we will look at
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below.
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<P>
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In this example, we configured named as the primary name server
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for three domains, as indicated by the primary statements
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at the end of the file. The first of these lines, for instance, instructs
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named to act as a primary server for vbrew.com, taking the
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zone data from the file named.hosts. The directory
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keyword tells it that all zone files are located in /var/named.
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<P>
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The cache entry is very special and should be present on
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virtually all machines running a name server. Its function is
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two-fold: it instructs named to enable its cache, and to load
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the <em>root name server hints</em> from the cache file specified
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(named.ca in our example). We will come back to the name server
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hints below.
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<P>
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Here's a list of the most important options you can use in
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named.boot:
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<dl>
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<dt> directory <dd>This specifies a directory in which zone files reside. Names
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of files may be given relative to this directory. Several
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directories may be specified by repeatedly using directory.
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According to the Linux filesystem standard, this should be
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/var/named.
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<dt> primary <dd>This takes a domain name and a file name as an argument,
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declaring the local server authoritative for the named domain.
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As a primary server, named loads the zone information from the
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given master file.
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Generally, there will always be at least one primary
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entry in every boot file, namely for reverse mapping of net-
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work 127.0.0.0, which is the local loopback network.
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<dt> secondary <dd> This statement takes a domain name, an address list, and a
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file name as an argument. It declares the local server a sec-
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ondary master server for the domain specified.
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A secondary server holds authoritative data on the
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domain, too, but it doesn't gather it from files, but tries to
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download it from the primary server. The IP address of at
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least one primary server must thus be given to named in the
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address list. The local server will contact each of them in
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turn until it successfully transfers the zone database, which
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is then stored in the backup file given as the third argument.
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If none of the primary servers responds, the zone data is
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retrieved from the backup file instead.
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named will then attempt to refresh the zone data at regu-
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lar intervals. This is explained below along in connection
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with the SOA resource record type.
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<dt>cache <dd>This takes a domain and a file name as arguments. This file
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contains the root server hints, that is a list of records
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pointing to the root name servers. Only NS and A records will
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be recognized. The domain argument is generally the root
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domain name ``.''.
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This information is absolutely crucial to named: if the
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cache statement does not occur in the boot file, named will
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not develop a local cache at all. This will severely degrade
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performance and increase network load if the next server
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queried is not on the local net. Moreover, named will not be
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able to reach any root name servers, and thus it won't resolve
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any addresses except those it is authoritative for. An excep-
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tion from this rule is when using forwarding servers (cf. the
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forwarders option below).
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<dt>forwarders <dd>This statement takes an address list as an argument. The IP
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addresses in this list specify a list of name servers that
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named may query if it fails to resolve a query from its local
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cache. They are tried in order until one of them responds to
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the query.
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<dt> slave <dd>This statement makes the name server a slave server. That is,
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it will never perform recursive queries itself, but only for-
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wards them to servers specified with the forwarders statement.
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</dl>
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There are two options which we will not describe here, being
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sortlist and domain. Additionally, there are two
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directives that may be used inside the zone database files. These are
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$INCLUDE and $ORIGIN. Since they are rarely
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needed, we will not describe them here, either.
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<HR><A HREF="node1.html"><IMG WIDTH=65 HEIGHT=24 ALIGN=BOTTOM ALT="contents" SRC="contents_motif.gif"></A> <BR>
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<B> Next:</B> <A HREF="node88.html">The DNS Database Files</A>
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<B>Up:</B> <A HREF="node86.html">Running named</A>
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<B> Previous:</B> <A HREF="node86.html">Running named</A>
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<P><ADDRESS>
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<I>Andrew Anderson <BR>
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Thu Mar 7 23:22:06 EST 1996</I>
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</ADDRESS>
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