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Reworded sections of "Reasons to run a name server" and changed

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definition of "Origin" in DNS section.

Reviewed by:	murray
This commit is contained in:
Chern Lee 2001-08-06 22:50:16 +00:00
parent 65edfaeafc
commit 8821260cc9
Notes: svn2git 2020-12-08 03:00:23 +00:00 
svn path=/head/; revision=10213
1 changed files with 49 additions and 64 deletions
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113
en_US.ISO8859-1/books/handbook/advanced-networking/chapter.sgml
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@ -1,7 +1,7 @@
<!--
The FreeBSD Documentation Project
$FreeBSD: doc/en_US.ISO8859-1/books/handbook/advanced-networking/chapter.sgml,v 1.68 2001/08/06 20:25:01 chern Exp $
$FreeBSD: doc/en_US.ISO8859-1/books/handbook/advanced-networking/chapter.sgml,v 1.69 2001/08/06 21:25:27 chern Exp $
-->
<chapter id="advanced-networking">
@ -3023,7 +3023,8 @@ dhcp_flags=""</programlisting>
<row>
<entry>origin</entry>
<entry>refers to the point of start for the particular zone</entry>
<entry>refers to the domain covered for the particular zone
file</entry>
</row>
<row>
@ -3106,69 +3107,53 @@ dhcp_flags=""</programlisting>
<sect2>
<title>Reasons to run a name server</title>
<itemizedlist>
<listitem>
<para>
A machine is needed to host DNS information to the world
</para>
<itemizedlist>
<listitem>
<para>An authoritative nameserver replies exclusively
to requests.
</para>
</listitem>
<listitem>
<para>For example, <hostid>foobardomain.org</hostid> is
registered and IP addresses need to be assigned to hostnames
under this domain.
</para>
</listitem>
<listitem>
<para>A slave nameserver, which replies to queries for a
domain when the primary is down or inaccessible.
</para>
</listitem>
<listitem>
<para>The above two can also be done with reverse DNS (IP
to hostname entries)
</para>
</listitem>
</itemizedlist>
</listitem>
<listitem>
<para>
A machine is needed to act as a local cache of DNS information
</para>
<itemizedlist>
<listitem>
<para>DNS traffic has been measured to be about 5% or more
of the total Internet traffic.
</para>
</listitem>
<listitem>
<para>A local DNS server may have some added benefit by
providing a local cache of DNS information.
</para>
</listitem>
<listitem>
<para>
For example, when one queries for
<hostid>www.freebsd.org</hostid>,
the resolver usually queries the uplink ISP's name
server, and retrieves the query.
</para>
</listitem>
<listitem>
<para>
With a local, caching DNS server, the query only has to
be made once to the outside world. Every additional
query will not have to look to the outside of the local
network, since the information is cached.
</para>
</listitem>
</itemizedlist>
</listitem>
<para>Name servers usually come in two forms: an authoritative
name server, and a caching nameserver.</para>
<para>An authoritative name server is needed when:</para>
<itemizedlist>
<listitem>
<para>one wants to serve DNS information to the
world, replying authoritatively to queries.</para>
</listitem>
<listitem>
<para>a domain, such as <hostid>foobardomain.org</hostid>, is
registered and IP addresses need to be assigned to hostnames
under it.</para>
</listitem>
<listitem>
<para>an IP address block requires reverse DNS entries (IP to
hostname).</para>
</listitem>
<listitem>
<para>a backup name server, called a slave, must reply to queries
when the primary is down or inaccessible.</para>
</listitem>
</itemizedlist>
<para>A caching name server is needed when:</para>
<itemizedlist>
<listitem>
<para>a local DNS server may cache and respond more quickly
then querying an outside name server.</para>
</listitem>
<listitem>
<para>a reduction in overall network traffic is desired. (DNS
traffic has been measured to account for 5% or more of total
Internet traffic)</para>
</listitem>
</itemizedlist>
<para>When one queries for <hostid>www.freebsd.org</hostid>, the
resolver usually queries the uplink ISP's name server, and retrieves
the reply. With a local, caching DNS server, the query only has to
be made once to the outside world by the caching DNS server. Every
additional query will not have to look to the outside of the local
network, since the information is cached locally.</para>
</sect2>
<sect2>