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&nbsp;&nbsp;&nbsp;be&nbsp;able&nbsp;to&nbsp;register&nbsp;a&nbsp;domain&nbsp;name&nbsp;for&nbsp;a&nbsp;whole&nbsp;university.&nbsp;&nbsp;The&nbsp;naming&nbsp;<BR>
&nbsp;&nbsp;&nbsp;authority&nbsp;can&nbsp;impose&nbsp;certain&nbsp;extra&nbsp;rules&nbsp;as&nbsp;long&nbsp;as&nbsp;they&nbsp;don't&nbsp;<BR>
&nbsp;&nbsp;&nbsp;violate&nbsp;or&nbsp;conflict&nbsp;with&nbsp;the&nbsp;rights&nbsp;and&nbsp;interest&nbsp;of&nbsp;the&nbsp;registrars&nbsp;of&nbsp;<BR>
&nbsp;&nbsp;&nbsp;subdomains;&nbsp;a&nbsp;top&nbsp;level&nbsp;domain&nbsp;registrar&nbsp;may&nbsp;e.g.,&nbsp;require&nbsp;that&nbsp;there&nbsp;<BR>
&nbsp;<BR>
&nbsp;<BR>
&nbsp;<BR>
Beertema&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;&nbsp;&nbsp;&nbsp;[Page&nbsp;7]&nbsp;<BR>
&nbsp;<BR>
RFC&nbsp;1537&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Common&nbsp;DNS&nbsp;Data&nbsp;File&nbsp;Configuration&nbsp;Errors&nbsp;&nbsp;&nbsp;&nbsp;October&nbsp;1993&nbsp;<BR>
&nbsp;<BR>
&nbsp;<BR>
&nbsp;&nbsp;&nbsp;be&nbsp;primary&nbsp;subdomain&nbsp;&quot;ac&quot;&nbsp;and&nbsp;&quot;co&quot;&nbsp;only&nbsp;and&nbsp;that&nbsp;subdomains&nbsp;be&nbsp;<BR>
&nbsp;&nbsp;&nbsp;registered&nbsp;under&nbsp;those&nbsp;primary&nbsp;subdomains.&nbsp;<BR>
&nbsp;<BR>
&nbsp;&nbsp;&nbsp;The&nbsp;naming&nbsp;authority&nbsp;can&nbsp;also&nbsp;interfere&nbsp;in&nbsp;exceptional&nbsp;cases&nbsp;like&nbsp;the&nbsp;<BR>
&nbsp;&nbsp;&nbsp;one&nbsp;mentioned&nbsp;in&nbsp;point&nbsp;4,&nbsp;e.g.,&nbsp;by&nbsp;temporarily&nbsp;removing&nbsp;a&nbsp;domain's&nbsp;<BR>
&nbsp;&nbsp;&nbsp;entry&nbsp;from&nbsp;the&nbsp;nameserver&nbsp;zone&nbsp;files;&nbsp;this&nbsp;of&nbsp;course&nbsp;should&nbsp;be&nbsp;done&nbsp;<BR>
&nbsp;&nbsp;&nbsp;only&nbsp;with&nbsp;extreme&nbsp;care&nbsp;and&nbsp;only&nbsp;as&nbsp;a&nbsp;last&nbsp;resort.&nbsp;<BR>
&nbsp;<BR>
&nbsp;&nbsp;&nbsp;When&nbsp;adding&nbsp;NS&nbsp;records&nbsp;for&nbsp;subdomains,&nbsp;top&nbsp;level&nbsp;domain&nbsp;nameserver&nbsp;<BR>
&nbsp;&nbsp;&nbsp;managers&nbsp;should&nbsp;realize&nbsp;that&nbsp;the&nbsp;people&nbsp;setting&nbsp;up&nbsp;the&nbsp;nameserver&nbsp;for&nbsp;<BR>
&nbsp;&nbsp;&nbsp;a&nbsp;subdomain&nbsp;often&nbsp;are&nbsp;rather&nbsp;inexperienced&nbsp;and&nbsp;can&nbsp;make&nbsp;mistakes&nbsp;that&nbsp;<BR>
&nbsp;&nbsp;&nbsp;can&nbsp;easily&nbsp;lead&nbsp;to&nbsp;the&nbsp;subdomain&nbsp;becoming&nbsp;completely&nbsp;unreachable&nbsp;or&nbsp;<BR>
&nbsp;&nbsp;&nbsp;that&nbsp;can&nbsp;cause&nbsp;unnecessary&nbsp;DNS&nbsp;traffic&nbsp;(see&nbsp;point&nbsp;1).&nbsp;It&nbsp;is&nbsp;therefore&nbsp;<BR>
&nbsp;&nbsp;&nbsp;highly&nbsp;recommended&nbsp;that,&nbsp;prior&nbsp;to&nbsp;entering&nbsp;such&nbsp;an&nbsp;NS&nbsp;record,&nbsp;the&nbsp;<BR>
&nbsp;&nbsp;&nbsp;(top&nbsp;level)&nbsp;nameserver&nbsp;manager&nbsp;does&nbsp;a&nbsp;couple&nbsp;of&nbsp;sanity&nbsp;checks&nbsp;on&nbsp;the&nbsp;<BR>
&nbsp;&nbsp;&nbsp;new&nbsp;nameserver&nbsp;(SOA&nbsp;record&nbsp;and&nbsp;timers&nbsp;OK?,&nbsp;MX&nbsp;records&nbsp;present&nbsp;where&nbsp;<BR>
&nbsp;&nbsp;&nbsp;needed?&nbsp;No&nbsp;obvious&nbsp;errors&nbsp;made?&nbsp;Listed&nbsp;secondary&nbsp;servers&nbsp;<BR>
&nbsp;&nbsp;&nbsp;operational?).&nbsp;Things&nbsp;that&nbsp;cannot&nbsp;be&nbsp;caught&nbsp;though&nbsp;by&nbsp;such&nbsp;checks&nbsp;<BR>
&nbsp;&nbsp;&nbsp;are:&nbsp;<BR>
&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;-&nbsp;resolvers&nbsp;set&nbsp;up&nbsp;to&nbsp;use&nbsp;external&nbsp;hosts&nbsp;as&nbsp;nameservers&nbsp;<BR>
&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;-&nbsp;nameservers&nbsp;set&nbsp;up&nbsp;to&nbsp;use&nbsp;external&nbsp;hosts&nbsp;as&nbsp;forwarders&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;without&nbsp;permission&nbsp;from&nbsp;those&nbsp;hosts.&nbsp;<BR>
&nbsp;<BR>
&nbsp;&nbsp;&nbsp;Care&nbsp;should&nbsp;also&nbsp;be&nbsp;taken&nbsp;when&nbsp;registering&nbsp;2-letter&nbsp;subdomains.&nbsp;<BR>
&nbsp;&nbsp;&nbsp;Although&nbsp;this&nbsp;is&nbsp;allowed,&nbsp;an&nbsp;implication&nbsp;is&nbsp;that&nbsp;abbreviated&nbsp;<BR>
&nbsp;&nbsp;&nbsp;addressing&nbsp;(see&nbsp;STD&nbsp;11,&nbsp;RFC&nbsp;822,&nbsp;paragraph&nbsp;6.2.2)&nbsp;is&nbsp;not&nbsp;possible&nbsp;in&nbsp;<BR>
&nbsp;&nbsp;&nbsp;and&nbsp;under&nbsp;that&nbsp;subdomain.&nbsp;&nbsp;When&nbsp;requested&nbsp;to&nbsp;register&nbsp;such&nbsp;a&nbsp;domain,&nbsp;<BR>
&nbsp;&nbsp;&nbsp;one&nbsp;should&nbsp;always&nbsp;notify&nbsp;the&nbsp;people&nbsp;of&nbsp;this&nbsp;consequence.&nbsp;As&nbsp;an&nbsp;<BR>
&nbsp;&nbsp;&nbsp;example&nbsp;take&nbsp;the&nbsp;name&nbsp;&quot;cs&quot;,&nbsp;which&nbsp;is&nbsp;commonly&nbsp;used&nbsp;for&nbsp;Computer&nbsp;<BR>
&nbsp;&nbsp;&nbsp;Science&nbsp;departments:&nbsp;it&nbsp;is&nbsp;also&nbsp;the&nbsp;name&nbsp;of&nbsp;the&nbsp;top&nbsp;level&nbsp;domain&nbsp;for&nbsp;<BR>
&nbsp;&nbsp;&nbsp;Czecho-Slovakia,&nbsp;so&nbsp;within&nbsp;the&nbsp;domain&nbsp;cs.foo.bar&nbsp;the&nbsp;<A HREF="mailto:[e-mail]">[e-mail]</A>&nbsp;is&nbsp;<BR>
&nbsp;&nbsp;&nbsp;ambiguous&nbsp;in&nbsp;that&nbsp;in&nbsp;can&nbsp;denote&nbsp;both&nbsp;a&nbsp;user&nbsp;on&nbsp;the&nbsp;host&nbsp;<BR>
&nbsp;&nbsp;&nbsp;host.cs.foo.bar&nbsp;and&nbsp;a&nbsp;user&nbsp;on&nbsp;the&nbsp;host&nbsp;&quot;host&quot;&nbsp;in&nbsp;Czecho-Slovakia.&nbsp;<BR>
&nbsp;&nbsp;&nbsp;(This&nbsp;example&nbsp;does&nbsp;not&nbsp;take&nbsp;into&nbsp;account&nbsp;the&nbsp;recent&nbsp;political&nbsp;changes&nbsp;<BR>
&nbsp;&nbsp;&nbsp;in&nbsp;the&nbsp;mentioned&nbsp;country).&nbsp;<BR>
&nbsp;<BR>
References&nbsp;<BR>
&nbsp;<BR>
&nbsp;&nbsp;&nbsp;[1]&nbsp;Mockapetris,&nbsp;P.,&nbsp;&quot;Domain&nbsp;Names&nbsp;Concepts&nbsp;and&nbsp;Facilities&quot;,&nbsp;STD&nbsp;13,&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;RFC&nbsp;1034,&nbsp;USC/Information&nbsp;Sciences&nbsp;Institute,&nbsp;November&nbsp;1987.&nbsp;<BR>
&nbsp;<BR>
&nbsp;&nbsp;&nbsp;[2]&nbsp;Mockapetris,&nbsp;P.,&nbsp;&quot;Domain&nbsp;Names&nbsp;Implementation&nbsp;and&nbsp;Specification&quot;,&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;STD&nbsp;13,&nbsp;RFC&nbsp;1035,&nbsp;USC/Information&nbsp;Sciences&nbsp;Institute,&nbsp;November&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;1987.&nbsp;<BR>
&nbsp;<BR>
&nbsp;<BR>
&nbsp;<BR>
&nbsp;<BR>
&nbsp;<BR>
Beertema&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;&nbsp;&nbsp;&nbsp;[Page&nbsp;8]&nbsp;<BR>
&nbsp;<BR>
RFC&nbsp;1537&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Common&nbsp;DNS&nbsp;Data&nbsp;File&nbsp;Configuration&nbsp;Errors&nbsp;&nbsp;&nbsp;&nbsp;October&nbsp;1993&nbsp;<BR>
&nbsp;<BR>
&nbsp;<BR>
&nbsp;&nbsp;&nbsp;[3]&nbsp;Partridge,&nbsp;C.,&nbsp;&quot;Mail&nbsp;Routing&nbsp;and&nbsp;the&nbsp;Domain&nbsp;System&quot;,&nbsp;STD&nbsp;14,&nbsp;RFC&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;974,&nbsp;CSNET&nbsp;CIC&nbsp;BBN,&nbsp;January&nbsp;1986.&nbsp;<BR>
&nbsp;<BR>
&nbsp;&nbsp;&nbsp;[4]&nbsp;Gavron,&nbsp;E.,&nbsp;&quot;A&nbsp;Security&nbsp;Problem&nbsp;and&nbsp;Proposed&nbsp;Correction&nbsp;With&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Widely&nbsp;Deployed&nbsp;DNS&nbsp;Software&quot;,&nbsp;RFC&nbsp;1535,&nbsp;ACES&nbsp;Research&nbsp;Inc.,&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;October&nbsp;1993.&nbsp;<BR>
&nbsp;<BR>
&nbsp;&nbsp;&nbsp;[5]&nbsp;Kumar,&nbsp;A.,&nbsp;Postel,&nbsp;J.,&nbsp;Neuman,&nbsp;C.,&nbsp;Danzig,&nbsp;P.,&nbsp;and&nbsp;S.&nbsp;Miller,&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&quot;Common&nbsp;DNS&nbsp;Implementation&nbsp;Errors&nbsp;and&nbsp;Suggested&nbsp;Fixes&quot;,&nbsp;RFC&nbsp;1536,&nbsp;<BR>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;USC/Information&nbsp;Sciences&nbsp;Institute,&nbsp;USC,&nbsp;October&nbsp;1993.&nbsp;<BR>
&nbsp;<BR>
Security&nbsp;Considerations&nbsp;<BR>
&nbsp;<BR>
&nbsp;&nbsp;&nbsp;Security&nbsp;issues&nbsp;are&nbsp;not&nbsp;discussed&nbsp;in&nbsp;this&nbsp;memo.&nbsp;<BR>
&nbsp;<BR>
Author's&nbsp;Address&nbsp;<BR>
&nbsp;<BR>
&nbsp;&nbsp;&nbsp;Piet&nbsp;Beertema&nbsp;<BR>
&nbsp;&nbsp;&nbsp;CWI&nbsp;<BR>
&nbsp;&nbsp;&nbsp;Kruislaan&nbsp;413&nbsp;<BR>
&nbsp;&nbsp;&nbsp;NL-1098&nbsp;SJ&nbsp;Amsterdam&nbsp;<BR>
&nbsp;&nbsp;&nbsp;The&nbsp;Netherlands&nbsp;<BR>
&nbsp;<BR>
&nbsp;&nbsp;&nbsp;Phone:&nbsp;+31&nbsp;20&nbsp;592&nbsp;4112&nbsp;<BR>
&nbsp;&nbsp;&nbsp;FAX:&nbsp;&nbsp;&nbsp;+31&nbsp;20&nbsp;592&nbsp;4199&nbsp;<BR>
&nbsp;&nbsp;&nbsp;EMail:&nbsp;<A HREF="mailto:[e-mail]">[e-mail]</A>&nbsp;<BR>
&nbsp;<BR>
&nbsp;<BR>
Editor's&nbsp;Address&nbsp;<BR>
&nbsp;<BR>
&nbsp;&nbsp;&nbsp;Anant&nbsp;Kumar&nbsp;<BR>
&nbsp;&nbsp;&nbsp;USC&nbsp;Information&nbsp;Sciences&nbsp;Institute&nbsp;<BR>
&nbsp;&nbsp;&nbsp;4676&nbsp;Admiralty&nbsp;Way&nbsp;<BR>
&nbsp;&nbsp;&nbsp;Marina&nbsp;Del&nbsp;Rey&nbsp;CA&nbsp;90292-6695&nbsp;<BR>
&nbsp;<BR>
&nbsp;&nbsp;&nbsp;Phone:(310)&nbsp;822-1511&nbsp;<BR>
&nbsp;&nbsp;&nbsp;FAX:&nbsp;&nbsp;(310)&nbsp;823-6741&nbsp;<BR>
&nbsp;&nbsp;&nbsp;EMail:&nbsp;<A HREF="mailto:[e-mail]">[e-mail]</A>&nbsp;<BR>
&nbsp;<BR>
&nbsp;<BR>
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&nbsp;<BR>
Beertema&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;&nbsp;&nbsp;&nbsp;[Page&nbsp;9]&nbsp;<BR>
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