Bv9ARM.ch01.html revision b9c96971964d87c2705c8dc29300ff8103479ee6
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>Introduction </TITLE
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceNAME="GENERATOR"
027e89d47af308db4b41761ca9f847c026b63ec8Andreas GustafssonCONTENT="Modular DocBook HTML Stylesheet Version 1.41"><LINK
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceREL="PREVIOUS"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceTITLE="BIND Resource Requirements"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceBGCOLOR="#FFFFFF"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceTEXT="#000000"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceLINK="#0000FF"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceVLINK="#840084"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceALINK="#0000FF"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="NAVHEADER"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCELLPADDING="0"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCELLSPACING="0"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceALIGN="center"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceVALIGN="bottom"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceALIGN="center"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceVALIGN="bottom"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceALIGN="right"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceVALIGN="bottom"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="chapter"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>Chapter 1. Introduction </A
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>Table of Contents</B
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>Scope of Document</A
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>Organization of This Document</A
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>Conventions Used in This Document</A
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>The Domain Name System (<SPAN
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="acronym"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>The Internet Domain Name System (<SPAN
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="acronym"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>) consists of the syntax
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce to specify the names of entities in the Internet in a hierarchical
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce manner, the rules used for delegating authority over names, and the
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce system implementation that actually maps names to Internet
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce addresses. <SPAN
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="acronym"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce> data is maintained in a group of distributed
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce hierarchical databases.</P
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="sect1"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="sect1"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>1.1. Scope of Document</A
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>The Berkeley Internet Name Domain (<SPAN
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="acronym"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>) implements an
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson domain name server for a number of operating systems. This
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce document provides basic information about the installation and
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce care of the Internet Software Consortium (<SPAN
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="acronym"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="acronym"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson> version 9 software package for system
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson administrators.</P
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>This version of the manual corresponds to BIND version 9.1.</P
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="sect1"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="sect1"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>1.2. Organization of This Document</A
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>In this document, <I
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="emphasis"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>Section 1</I
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce the basic <SPAN
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="acronym"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="acronym"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce> concepts. <I
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="emphasis"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>Section 2</I
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce describes resource requirements for running <SPAN
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="acronym"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce environments. Information in <I
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="emphasis"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>Section 3</I
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="emphasis"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>task-oriented</I
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce> in its presentation and is
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce organized functionally, to aid in the process of installing the
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="acronym"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce> 9 software. The task-oriented section is followed by
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="emphasis"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>Section 4</I
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>, which contains more advanced
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce concepts that the system administrator may need for implementing
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson certain options. <I
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="emphasis"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson describes the <SPAN
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="acronym"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce> 9 lightweight
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce resolver. The contents of <I
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="emphasis"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>Section 6</I
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce organized as in a reference manual to aid in the ongoing
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce maintenance of the software. <I
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="emphasis"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>addresses security considerations, and
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="emphasis"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>Section 8</I
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce> contains troubleshooting help. The
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce main body of the document is followed by several
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="emphasis"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>Appendices</I
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce> which contain useful reference
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce information, such as a <I
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="emphasis"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>Bibliography</I
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce historic information related to <SPAN
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="acronym"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce> and the Domain Name
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="sect1"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="sect1"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>1.3. Conventions Used in This Document</A
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>In this document, we use the following general typographic
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce conventions:</P
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="informaltable"
aeb8fffc841865c3336383eadfd9987332a03286Andreas GustafssonCELLPADDING="3"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="CALSTABLE"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceVALIGN="MIDDLE"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="emphasis"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceVALIGN="MIDDLE"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="emphasis"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>We use the style:</I
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceVALIGN="MIDDLE"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>a pathname, filename, URL, hostname,
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Lucemailing list name, or new term or concept</P
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceVALIGN="MIDDLE"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="filename"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>Fixed width</TT
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceVALIGN="MIDDLE"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>literal user
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceVALIGN="MIDDLE"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="userinput"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>Fixed Width Bold</B
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceVALIGN="MIDDLE"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>program output</P
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceVALIGN="MIDDLE"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="computeroutput"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>Fixed Width</TT
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>The following conventions are used in descriptions of the
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="acronym"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce> configuration file:<DIV
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="informaltable"
aeb8fffc841865c3336383eadfd9987332a03286Andreas GustafssonCELLPADDING="3"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="CALSTABLE"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceVALIGN="MIDDLE"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="emphasis"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceVALIGN="MIDDLE"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="emphasis"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>We use the style:</I
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceVALIGN="MIDDLE"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceVALIGN="MIDDLE"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="literal"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>Fixed Width</TT
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceVALIGN="MIDDLE"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>variables</P
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceVALIGN="MIDDLE"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="varname"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>Fixed Width</TT
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceVALIGN="MIDDLE"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>Optional input</P
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceVALIGN="MIDDLE"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="optional"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>Text is enclosed in square brackets</SPAN
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="sect1"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="sect1"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>1.4. The Domain Name System (<SPAN
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="acronym"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>The purpose of this document is to explain the installation
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonand upkeep of the <SPAN
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="acronym"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson> software package, and we
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonbegin by reviewing the fundamentals of the Domain Name System
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="acronym"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>) as they relate to <SPAN
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="acronym"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>1.4.1. DNS Fundamentals</A
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>The Domain Name System (DNS) is the hierarchical, distributed
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssondatabase. It stores information for mapping Internet host names to IP
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonaddresses and vice versa, mail routing information, and other data
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonused by Internet applications.</P
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>Clients look up information in the DNS by calling a
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="emphasis"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson> library, which sends queries to one or
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="emphasis"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>name servers</I
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson> and interprets the responses.
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="acronym"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson> software distribution contains both a
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonname server and a resolver library.</P
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="sect2"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="sect2"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>1.4.2. Domains and Domain Names</A
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>The data stored in the DNS is identified by <I
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="emphasis"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson> that are organized as a tree according to
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonorganizational or administrative boundaries. Each node of the tree,
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="emphasis"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>, is given a label. The domain name of the
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonnode is the concatenation of all the labels on the path from the
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="emphasis"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson> node. This is represented
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonin written form as a string of labels listed from right to left and
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonseparated by dots. A label need only be unique within its parent
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>For example, a domain name for a host at the
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="emphasis"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>Example, Inc.</I
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="literal"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="literal"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssontop level domain to which
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="literal"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="literal"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssona subdomain of <TT
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="literal"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="literal"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Lucename of the host.</P
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>For administrative purposes, the name space is partitioned into
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonareas called <I
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="emphasis"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>, each starting at a node and
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonextending down to the leaf nodes or to nodes where other zones start.
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonThe data for each zone is stored in a <I
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="emphasis"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>, which answers queries about the zone using the
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="emphasis"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>DNS protocol</I
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>The data associated with each domain name is stored in the
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="emphasis"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>resource records</I
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="acronym"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonSome of the supported resource record types are described in
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonHREF="Bv9ARM.ch06.html#types_of_resource_records_and_when_to_use_them"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>Section 6.3.1</A
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>For more detailed information about the design of the DNS and
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonthe DNS protocol, please refer to the standards documents listed in
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>Section A.4.1</A
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="sect2"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="sect2"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>1.4.3. Zones</A
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>To properly operate a name server, it is important to understand
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonthe difference between a <I
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="emphasis"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="emphasis"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>As we stated previously, a zone is a point of delegation in
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="acronym"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson> tree. A zone consists of
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonthose contiguous parts of the domain
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssontree for which a a name server has complete information and over which
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luceit has authority. It contains all domain names from a certain point
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Lucedownward in the domain tree except those which are delegated to
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonother zones. A delegation point is marked by one or more
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="emphasis"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luceparent zone, which should be matched by equivalent NS records at
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Lucethe root of the delegated zone.</P
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>For instance, consider the <TT
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="literal"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssondomain which includes names
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="literal"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="literal"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="literal"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson> zone includes
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssononly delegations for the <TT
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="literal"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="literal"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson> zones. A zone can map
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonexactly to a single domain, but could also include only part of a
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssondomain, the rest of which could be delegated to other
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonname servers. Every name in the <SPAN
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="acronym"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="emphasis"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>, even if it is
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="emphasis"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>, that is, has no
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="emphasis"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>subdomains</I
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>. Every subdomain is a domain and
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonevery domain except the root is also a subdomain. The terminology is
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonnot intuitive and we suggest that you read RFCs 1033, 1034 and 1035 to
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssongain a complete understanding of this difficult and subtle
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce>Though <SPAN
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="acronym"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson> is called a "domain name server",
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonit deals primarily in terms of zones. The master and slave
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssondeclarations in the <TT
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="filename"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonzones, not domains. When you ask some other site if it is willing to
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonbe a slave server for your <I
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="emphasis"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luceactually asking for slave service for some collection of zones.</P
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="sect2"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="sect2"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>1.4.4. Authoritative Name Servers</A
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>Each zone is served by at least
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="emphasis"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>authoritative name server</I
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonwhich contains the complete data for the zone.
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonTo make the DNS tolerant of server and network failures,
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonmost zones have two or more authoritative servers.
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>Responses from authoritative servers have the the "authoritative
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonanswer" (AA) bit set in the response packets. This makes them
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssoneasy to identify when debugging DNS configurations using tools like
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="command"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonHREF="Bv9ARM.ch03.html#diagnostic_tools"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>Section 3.4.1.1</A
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="sect3"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="sect3"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>1.4.4.1. The Primary Master</A
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson> The authoritative server where the master copy of the zone data is maintained is
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="emphasis"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>primary master</I
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson> server, or simply the
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="emphasis"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>. It loads the zone contents from some
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonlocal file edited by humans or perhaps generated mechanically from
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonsome other local file which is edited by humans. This file is called
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="emphasis"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="emphasis"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>master file</I
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="sect3"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="sect3"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>1.4.4.2. Slave Servers</A
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>The other authoritative servers, the <I
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="emphasis"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonservers (also known as <I
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="emphasis"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson> servers) load
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonthe zone contents from another server using a replication process
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="emphasis"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>zone transfer</I
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>. Typically the data are
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssontransferred directly from the primary master, but it is also possible
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonto transfer it from another slave. In other words, a slave server
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonmay itself act as a master to a subordinate slave server.</P
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="sect3"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="sect3"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>1.4.4.3. Stealth Servers</A
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>Usually all of the zone's authoritative servers are listed in
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonNS records in the parent zone. These NS records constitute
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="emphasis"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson> of the zone from the parent.
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonThe authoritative servers are also listed in the zone file itself,
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="emphasis"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="emphasis"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonof the zone. You can list servers in the zone's top-level NS
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonrecords that are not in the parent's NS delegation, but you cannot
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonlist servers in the parent's delegation that are not present at
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonthe zone's top level.</P
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="emphasis"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>stealth server</I
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson> is a server that is
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonauthoritative for a zone but is not listed in that zone's NS
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonrecords. Stealth servers can be used for keeping a local copy of a
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonzone to speed up access to the zone's records or to make sure that the
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonzone is available even if all the "official" servers for the zone are
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssoninaccessible.</P
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>A configuration where the primary master server itself is a
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonstealth server is often referred to as a "hidden primary"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonconfiguration. One use for this configuration is when the primary master
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonis behind a firewall and therefore unable to communicate directly
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonwith the outside world.</P
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>1.4.5. Caching Name Servers</A
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>The resolver libraries provided by most operating systems are
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="emphasis"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>stub resolvers</I
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>, meaning that they are not capable of
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonperforming the full DNS resolution process by themselves by talking
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssondirectly to the authoritative servers. Instead, they rely on a local
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonname server to perform the resolution on their behalf. Such a server
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="emphasis"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson> name server; it performs
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="emphasis"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>recursive lookups</I
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson> for local clients.</P
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>To improve performance, recursive servers cache the results of
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonthe lookups they perform. Since the processes of recursion and
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssoncaching are intimately connected, the terms
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="emphasis"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>recursive server</I
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="emphasis"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>caching server</I
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson> are often used synonymously.</P
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>The length of time for which a record may be retained in
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonin the cache of a caching name server is controlled by the
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonTime To Live (TTL) field associated with each resource record.
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="sect3"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="sect3"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>1.4.5.1. Forwarding</A
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>Even a caching name server does not necessarily perform
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonthe complete recursive lookup itself. Instead, it can
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="emphasis"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson> some or all of the queries
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonthat it cannot satisfy from its cache to another caching name server,
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssoncommonly referred to as a <I
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="emphasis"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>There may be one or more forwarders,
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luceand they are queried in turn until the list is exhausted or an answer
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonis found. Forwarders are typically used when you do not
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonwish all the servers at a given site to interact directly with the rest of
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Lucethe Internet servers. A typical scenario would involve a number
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luceof internal <SPAN
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="acronym"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce> servers and an Internet firewall. Servers unable
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luceto pass packets through the firewall would forward to the server
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Lucethat can do it, and that server would query the Internet <SPAN
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="acronym"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luceon the internal server's behalf. An added benefit of using the forwarding
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Lucefeature is that the central machine develops a much more complete
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssoncache of information that all the clients can take advantage
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>1.4.6. Name Servers in Multiple Roles</A
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="acronym"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson> name server can simultaneously act as
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssona master for some zones, a slave for other zones, and as a caching
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson(recursive) server for a set of local clients.</P
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>However, since the functions of authoritative name service
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonand caching/recursive name service are logically separate, it is
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonoften advantageous to run them on separate server machines.
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonA server that only provides authoritative name service
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="emphasis"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>authoritative-only</I
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson> server) can run with
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonrecursion disabled, improving reliability and security.
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonA server that is not authoritative for any zones and only provides
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonrecursive service to local
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas GustafssonCLASS="emphasis"
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafsson>caching-only</I
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssondoes not need to be reachable from the Internet at large and can
b9c96971964d87c2705c8dc29300ff8103479ee6Andreas Gustafssonbe placed inside a firewall.</P
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="NAVFOOTER"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCELLPADDING="0"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCELLSPACING="0"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceALIGN="center"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceALIGN="right"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceALIGN="center"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceALIGN="right"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric LuceCLASS="acronym"
f293a69bcd1c1dd7bdac8f4102fc2398b9e475c8Eric Luce> Resource Requirements</TD