00000004.htm

一份很好的linux入门资料

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;speed&nbsp;of&nbsp;updates,&nbsp;and&nbsp;the&nbsp;accuracy&nbsp;of&nbsp;caches,&nbsp;the&nbsp;source&nbsp;of&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;the&nbsp;data&nbsp;should&nbsp;control&nbsp;the&nbsp;tradeoff.&nbsp;<BR>
&nbsp;<BR>
&nbsp;&nbsp;&nbsp;-&nbsp;The&nbsp;costs&nbsp;of&nbsp;implementing&nbsp;such&nbsp;a&nbsp;facility&nbsp;dictate&nbsp;that&nbsp;it&nbsp;be&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;generally&nbsp;useful,&nbsp;and&nbsp;not&nbsp;restricted&nbsp;to&nbsp;a&nbsp;single&nbsp;application.&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;We&nbsp;should&nbsp;be&nbsp;able&nbsp;to&nbsp;use&nbsp;names&nbsp;to&nbsp;retrieve&nbsp;host&nbsp;addresses,&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;mailbox&nbsp;data,&nbsp;and&nbsp;other&nbsp;as&nbsp;yet&nbsp;undetermined&nbsp;information.&nbsp;&nbsp;All&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;data&nbsp;associated&nbsp;with&nbsp;a&nbsp;name&nbsp;is&nbsp;tagged&nbsp;with&nbsp;a&nbsp;type,&nbsp;and&nbsp;queries&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;can&nbsp;be&nbsp;limited&nbsp;to&nbsp;a&nbsp;single&nbsp;type.&nbsp;<BR>
&nbsp;<BR>
&nbsp;&nbsp;&nbsp;-&nbsp;Because&nbsp;we&nbsp;want&nbsp;the&nbsp;name&nbsp;space&nbsp;to&nbsp;be&nbsp;useful&nbsp;in&nbsp;dissimilar&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;networks&nbsp;and&nbsp;applications,&nbsp;we&nbsp;provide&nbsp;the&nbsp;ability&nbsp;to&nbsp;use&nbsp;the&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;same&nbsp;name&nbsp;space&nbsp;with&nbsp;different&nbsp;protocol&nbsp;families&nbsp;or&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;management.&nbsp;&nbsp;For&nbsp;example,&nbsp;host&nbsp;address&nbsp;formats&nbsp;differ&nbsp;between&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;protocols,&nbsp;though&nbsp;all&nbsp;protocols&nbsp;have&nbsp;the&nbsp;notion&nbsp;of&nbsp;address.&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;The&nbsp;DNS&nbsp;tags&nbsp;all&nbsp;data&nbsp;with&nbsp;a&nbsp;class&nbsp;as&nbsp;well&nbsp;as&nbsp;the&nbsp;type,&nbsp;so&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;that&nbsp;we&nbsp;can&nbsp;allow&nbsp;parallel&nbsp;use&nbsp;of&nbsp;different&nbsp;formats&nbsp;for&nbsp;data&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;of&nbsp;type&nbsp;address.&nbsp;<BR>
&nbsp;<BR>
&nbsp;&nbsp;&nbsp;-&nbsp;We&nbsp;want&nbsp;name&nbsp;server&nbsp;transactions&nbsp;to&nbsp;be&nbsp;independent&nbsp;of&nbsp;the&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;communications&nbsp;system&nbsp;that&nbsp;carries&nbsp;them.&nbsp;&nbsp;Some&nbsp;systems&nbsp;may&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;wish&nbsp;to&nbsp;use&nbsp;datagrams&nbsp;for&nbsp;queries&nbsp;and&nbsp;responses,&nbsp;and&nbsp;only&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;establish&nbsp;virtual&nbsp;circuits&nbsp;for&nbsp;transactions&nbsp;that&nbsp;need&nbsp;the&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;reliability&nbsp;(e.g.,&nbsp;database&nbsp;updates,&nbsp;long&nbsp;transactions);&nbsp;other&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;systems&nbsp;will&nbsp;use&nbsp;virtual&nbsp;circuits&nbsp;exclusively.&nbsp;<BR>
&nbsp;<BR>
&nbsp;&nbsp;&nbsp;-&nbsp;The&nbsp;system&nbsp;should&nbsp;be&nbsp;useful&nbsp;across&nbsp;a&nbsp;wide&nbsp;spectrum&nbsp;of&nbsp;host&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;capabilities.&nbsp;&nbsp;Both&nbsp;personal&nbsp;computers&nbsp;and&nbsp;large&nbsp;timeshared&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;hosts&nbsp;should&nbsp;be&nbsp;able&nbsp;to&nbsp;use&nbsp;the&nbsp;system,&nbsp;though&nbsp;perhaps&nbsp;in&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;different&nbsp;ways.&nbsp;<BR>
&nbsp;<BR>
2.3.&nbsp;Assumptions&nbsp;about&nbsp;usage&nbsp;<BR>
&nbsp;<BR>
The&nbsp;organization&nbsp;of&nbsp;the&nbsp;domain&nbsp;system&nbsp;derives&nbsp;from&nbsp;some&nbsp;assumptions&nbsp;<BR>
about&nbsp;the&nbsp;needs&nbsp;and&nbsp;usage&nbsp;patterns&nbsp;of&nbsp;its&nbsp;user&nbsp;community&nbsp;and&nbsp;is&nbsp;designed&nbsp;<BR>
to&nbsp;avoid&nbsp;many&nbsp;of&nbsp;the&nbsp;the&nbsp;complicated&nbsp;problems&nbsp;found&nbsp;in&nbsp;general&nbsp;purpose&nbsp;<BR>
database&nbsp;systems.&nbsp;<BR>
&nbsp;<BR>
The&nbsp;assumptions&nbsp;are:&nbsp;<BR>
&nbsp;<BR>
&nbsp;&nbsp;&nbsp;-&nbsp;The&nbsp;size&nbsp;of&nbsp;the&nbsp;total&nbsp;database&nbsp;will&nbsp;initially&nbsp;be&nbsp;proportional&nbsp;<BR>
&nbsp;<BR>
&nbsp;<BR>
&nbsp;<BR>
Mockapetris&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[Page&nbsp;3]&nbsp;<BR>
&nbsp;<BR>
RFC&nbsp;1034&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Domain&nbsp;Concepts&nbsp;and&nbsp;Facilities&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;November&nbsp;1987&nbsp;<BR>
&nbsp;<BR>
&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;to&nbsp;the&nbsp;number&nbsp;of&nbsp;hosts&nbsp;using&nbsp;the&nbsp;system,&nbsp;but&nbsp;will&nbsp;eventually&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;grow&nbsp;to&nbsp;be&nbsp;proportional&nbsp;to&nbsp;the&nbsp;number&nbsp;of&nbsp;users&nbsp;on&nbsp;those&nbsp;hosts&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;as&nbsp;mailboxes&nbsp;and&nbsp;other&nbsp;information&nbsp;are&nbsp;added&nbsp;to&nbsp;the&nbsp;domain&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;system.&nbsp;<BR>
&nbsp;<BR>
&nbsp;&nbsp;&nbsp;-&nbsp;Most&nbsp;of&nbsp;the&nbsp;data&nbsp;in&nbsp;the&nbsp;system&nbsp;will&nbsp;change&nbsp;very&nbsp;slowly&nbsp;(e.g.,&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;mailbox&nbsp;bindings,&nbsp;host&nbsp;addresses),&nbsp;but&nbsp;that&nbsp;the&nbsp;system&nbsp;should&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;be&nbsp;able&nbsp;to&nbsp;deal&nbsp;with&nbsp;subsets&nbsp;that&nbsp;change&nbsp;more&nbsp;rapidly&nbsp;(on&nbsp;the&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;order&nbsp;of&nbsp;seconds&nbsp;or&nbsp;minutes).&nbsp;<BR>
&nbsp;<BR>
&nbsp;&nbsp;&nbsp;-&nbsp;The&nbsp;administrative&nbsp;boundaries&nbsp;used&nbsp;to&nbsp;distribute&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;responsibility&nbsp;for&nbsp;the&nbsp;database&nbsp;will&nbsp;usually&nbsp;correspond&nbsp;to&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;organizations&nbsp;that&nbsp;have&nbsp;one&nbsp;or&nbsp;more&nbsp;hosts.&nbsp;&nbsp;Each&nbsp;organization&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;that&nbsp;has&nbsp;responsibility&nbsp;for&nbsp;a&nbsp;particular&nbsp;set&nbsp;of&nbsp;domains&nbsp;will&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;provide&nbsp;redundant&nbsp;name&nbsp;servers,&nbsp;either&nbsp;on&nbsp;the&nbsp;organization's&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;own&nbsp;hosts&nbsp;or&nbsp;other&nbsp;hosts&nbsp;that&nbsp;the&nbsp;organization&nbsp;arranges&nbsp;to&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;use.&nbsp;<BR>
&nbsp;<BR>
&nbsp;&nbsp;&nbsp;-&nbsp;Clients&nbsp;of&nbsp;the&nbsp;domain&nbsp;system&nbsp;should&nbsp;be&nbsp;able&nbsp;to&nbsp;identify&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;trusted&nbsp;name&nbsp;servers&nbsp;they&nbsp;prefer&nbsp;to&nbsp;use&nbsp;before&nbsp;accepting&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;referrals&nbsp;to&nbsp;name&nbsp;servers&nbsp;outside&nbsp;of&nbsp;this&nbsp;&quot;trusted&quot;&nbsp;set.&nbsp;<BR>
&nbsp;<BR>
&nbsp;&nbsp;&nbsp;-&nbsp;Access&nbsp;to&nbsp;information&nbsp;is&nbsp;more&nbsp;critical&nbsp;than&nbsp;instantaneous&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;updates&nbsp;or&nbsp;guarantees&nbsp;of&nbsp;consistency.&nbsp;&nbsp;Hence&nbsp;the&nbsp;update&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;process&nbsp;allows&nbsp;updates&nbsp;to&nbsp;percolate&nbsp;out&nbsp;through&nbsp;the&nbsp;users&nbsp;of&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;the&nbsp;domain&nbsp;system&nbsp;rather&nbsp;than&nbsp;guaranteeing&nbsp;that&nbsp;all&nbsp;copies&nbsp;are&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;simultaneously&nbsp;updated.&nbsp;&nbsp;When&nbsp;updates&nbsp;are&nbsp;unavailable&nbsp;due&nbsp;to&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;network&nbsp;or&nbsp;host&nbsp;failure,&nbsp;the&nbsp;usual&nbsp;course&nbsp;is&nbsp;to&nbsp;believe&nbsp;old&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;information&nbsp;while&nbsp;continuing&nbsp;efforts&nbsp;to&nbsp;update&nbsp;it.&nbsp;&nbsp;The&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;general&nbsp;model&nbsp;is&nbsp;that&nbsp;copies&nbsp;are&nbsp;distributed&nbsp;with&nbsp;timeouts&nbsp;for&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;refreshing.&nbsp;&nbsp;The&nbsp;distributor&nbsp;sets&nbsp;the&nbsp;timeout&nbsp;value&nbsp;and&nbsp;the&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;recipient&nbsp;of&nbsp;the&nbsp;distribution&nbsp;is&nbsp;responsible&nbsp;for&nbsp;performing&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;the&nbsp;refresh.&nbsp;&nbsp;In&nbsp;special&nbsp;situations,&nbsp;very&nbsp;short&nbsp;intervals&nbsp;can&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;be&nbsp;specified,&nbsp;or&nbsp;the&nbsp;owner&nbsp;can&nbsp;prohibit&nbsp;copies.&nbsp;<BR>
&nbsp;<BR>
&nbsp;&nbsp;&nbsp;-&nbsp;In&nbsp;any&nbsp;system&nbsp;that&nbsp;has&nbsp;a&nbsp;distributed&nbsp;database,&nbsp;a&nbsp;particular&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;name&nbsp;server&nbsp;may&nbsp;be&nbsp;presented&nbsp;with&nbsp;a&nbsp;query&nbsp;that&nbsp;can&nbsp;only&nbsp;be&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;answered&nbsp;by&nbsp;some&nbsp;other&nbsp;server.&nbsp;&nbsp;The&nbsp;two&nbsp;general&nbsp;approaches&nbsp;to&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;dealing&nbsp;with&nbsp;this&nbsp;problem&nbsp;are&nbsp;&quot;recursive&quot;,&nbsp;in&nbsp;which&nbsp;the&nbsp;first&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;server&nbsp;pursues&nbsp;the&nbsp;query&nbsp;for&nbsp;the&nbsp;client&nbsp;at&nbsp;another&nbsp;server,&nbsp;and&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&quot;iterative&quot;,&nbsp;in&nbsp;which&nbsp;the&nbsp;server&nbsp;refers&nbsp;the&nbsp;client&nbsp;to&nbsp;another&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;server&nbsp;and&nbsp;lets&nbsp;the&nbsp;client&nbsp;pursue&nbsp;the&nbsp;query.&nbsp;&nbsp;Both&nbsp;approaches&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;have&nbsp;advantages&nbsp;and&nbsp;disadvantages,&nbsp;but&nbsp;the&nbsp;iterative&nbsp;approach&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;is&nbsp;preferred&nbsp;for&nbsp;the&nbsp;datagram&nbsp;style&nbsp;of&nbsp;access.&nbsp;&nbsp;The&nbsp;domain&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;system&nbsp;requires&nbsp;implementation&nbsp;of&nbsp;the&nbsp;iterative&nbsp;approach,&nbsp;but&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;allows&nbsp;the&nbsp;recursive&nbsp;approach&nbsp;as&nbsp;an&nbsp;option.&nbsp;<BR>
&nbsp;<BR>
&nbsp;<BR>
&nbsp;<BR>
&nbsp;<BR>
&nbsp;<BR>
Mockapetris&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[Page&nbsp;4]&nbsp;<BR>
&nbsp;<BR>
RFC&nbsp;1034&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Domain&nbsp;Concepts&nbsp;and&nbsp;Facilities&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;November&nbsp;1987&nbsp;<BR>
&nbsp;<BR>
&nbsp;<BR>
The&nbsp;domain&nbsp;system&nbsp;assumes&nbsp;that&nbsp;all&nbsp;data&nbsp;originates&nbsp;in&nbsp;master&nbsp;files&nbsp;<BR>
scattered&nbsp;through&nbsp;the&nbsp;hosts&nbsp;that&nbsp;use&nbsp;the&nbsp;domain&nbsp;system.&nbsp;&nbsp;These&nbsp;master&nbsp;<BR>
files&nbsp;are&nbsp;updated&nbsp;by&nbsp;local&nbsp;system&nbsp;administrators.&nbsp;&nbsp;Master&nbsp;files&nbsp;are&nbsp;text&nbsp;<BR>
files&nbsp;that&nbsp;are&nbsp;read&nbsp;by&nbsp;a&nbsp;local&nbsp;name&nbsp;server,&nbsp;and&nbsp;hence&nbsp;become&nbsp;available&nbsp;<BR>
through&nbsp;the&nbsp;name&nbsp;servers&nbsp;to&nbsp;users&nbsp;of&nbsp;the&nbsp;domain&nbsp;system.&nbsp;&nbsp;The&nbsp;user&nbsp;<BR>
programs&nbsp;access&nbsp;name&nbsp;servers&nbsp;through&nbsp;standard&nbsp;programs&nbsp;called&nbsp;resolvers.&nbsp;<BR>
&nbsp;<BR>
The&nbsp;standard&nbsp;format&nbsp;of&nbsp;master&nbsp;files&nbsp;allows&nbsp;them&nbsp;to&nbsp;be&nbsp;exchanged&nbsp;between&nbsp;<BR>
hosts&nbsp;(via&nbsp;FTP,&nbsp;mail,&nbsp;or&nbsp;some&nbsp;other&nbsp;mechanism);&nbsp;this&nbsp;facility&nbsp;is&nbsp;useful&nbsp;<BR>
when&nbsp;an&nbsp;organization&nbsp;wants&nbsp;a&nbsp;domain,&nbsp;but&nbsp;doesn't&nbsp;want&nbsp;to&nbsp;support&nbsp;a&nbsp;name&nbsp;<BR>
server.&nbsp;&nbsp;The&nbsp;organization&nbsp;can&nbsp;maintain&nbsp;the&nbsp;master&nbsp;files&nbsp;locally&nbsp;using&nbsp;a&nbsp;<BR>
text&nbsp;editor,&nbsp;transfer&nbsp;them&nbsp;to&nbsp;a&nbsp;foreign&nbsp;host&nbsp;which&nbsp;runs&nbsp;a&nbsp;name&nbsp;server,&nbsp;<BR>
and&nbsp;then&nbsp;arrange&nbsp;with&nbsp;the&nbsp;system&nbsp;administrator&nbsp;of&nbsp;the&nbsp;name&nbsp;server&nbsp;to&nbsp;get&nbsp;<BR>
the&nbsp;files&nbsp;loaded.&nbsp;<BR>
&nbsp;<BR>
Each&nbsp;host's&nbsp;name&nbsp;servers&nbsp;and&nbsp;resolvers&nbsp;are&nbsp;configured&nbsp;by&nbsp;a&nbsp;local&nbsp;system&nbsp;<BR>
administrator&nbsp;[RFC-1033].&nbsp;&nbsp;For&nbsp;a&nbsp;name&nbsp;server,&nbsp;this&nbsp;configuration&nbsp;data&nbsp;<BR>
includes&nbsp;the&nbsp;identity&nbsp;of&nbsp;local&nbsp;master&nbsp;files&nbsp;and&nbsp;instructions&nbsp;on&nbsp;which&nbsp;<BR>
non-local&nbsp;master&nbsp;files&nbsp;are&nbsp;to&nbsp;be&nbsp;loaded&nbsp;from&nbsp;foreign&nbsp;servers.&nbsp;&nbsp;The&nbsp;name&nbsp;<BR>
server&nbsp;uses&nbsp;the&nbsp;master&nbsp;files&nbsp;or&nbsp;copies&nbsp;to&nbsp;load&nbsp;its&nbsp;zones.&nbsp;&nbsp;For&nbsp;<BR>
resolvers,&nbsp;the&nbsp;configuration&nbsp;data&nbsp;identifies&nbsp;the&nbsp;name&nbsp;servers&nbsp;which&nbsp;<BR>
should&nbsp;be&nbsp;the&nbsp;primary&nbsp;sources&nbsp;of&nbsp;information.&nbsp;<BR>
&nbsp;<BR>
The&nbsp;domain&nbsp;system&nbsp;defines&nbsp;procedures&nbsp;for&nbsp;accessing&nbsp;the&nbsp;data&nbsp;and&nbsp;for&nbsp;<BR>