{"id":356,"date":"2010-07-27T14:26:10","date_gmt":"2010-07-27T13:26:10","guid":{"rendered":"http:\/\/blogs.oucs.ox.ac.uk\/networks\/?p=356"},"modified":"2010-07-27T14:26:10","modified_gmt":"2010-07-27T13:26:10","slug":"relaxing-the-dns-cname-rules-a-little","status":"publish","type":"post","link":"https:\/\/blogs-new.it.ox.ac.uk\/networks\/2010\/07\/27\/relaxing-the-dns-cname-rules-a-little\/","title":{"rendered":"Relaxing the DNS CNAME rules (a little)"},"content":{"rendered":"<p>In the University we have a web tool which allows IT Staff to update parts of the DNS covering their own unit. It&#8217;s a simple tool which we hope one day to replace, but serves well enough for most cases for the time being.<\/p>\n<p>One restriction coded into the tool is that when creating a CNAME, the alias itself and also the target of the alias must both be within the IT Officer&#8217;s own <em>ox.ac.uk<\/em> subdomain(s). For example, assuming we are an Engineering Science IT Officer:<\/p>\n<pre>test1.eng --&gt; www.eng   OK\r\ntest2.eng --&gt; www.chem  FAIL<\/pre>\n<p>However a good number of units in the University are collaborating on, sharing or leasing IT services from other units, often requiring cross-unit CNAMEs to be in place. IT Officers email Hostmaster to ask for such records to be created, and my team does that for them. However we&#8217;re aware that we add no value to this process, as we&#8217;re not checking the validity of the CNAME target other than that it&#8217;s within the <em>ox.ac.uk<\/em> domain. If we add no value to a process as humans, it&#8217;s a good candidate for automating away!<\/p>\n<p>Therefore we&#8217;ve recently rolled out a change to the DNS web admin tool that allows the <em>target<\/em> of a CNAME to be the name of any other A record within the University. The CNAME itself must still be within the IT Officer&#8217;s permitted DNS subdomains, but now they are free to point at any other A record&#8217;s name in <em>ox.ac.uk<\/em>:<\/p>\n<pre>test1.eng --&gt; www.eng   OK\r\ntest2.eng --&gt; www.chem  OK<\/pre>\n<p>I hope this proves welcome from those collaborating within the University!<\/p>\n<p><em>p.s.<\/em> In the web tool, as above in the examples, you omit the <em>ox.ac.uk<\/em> from host names just to save effort. However when configuring your hosts don&#8217;t forget that the fully-qualified name does include <em>.ox.ac.uk<\/em> on the end!<\/p>\n","protected":false},"excerpt":{"rendered":"<p>In the University we have a web tool which allows IT Staff to update parts of the DNS covering their own unit. It&#8217;s a simple tool which we hope one day to replace, but serves well enough for most cases &hellip; <a href=\"https:\/\/blogs-new.it.ox.ac.uk\/networks\/2010\/07\/27\/relaxing-the-dns-cname-rules-a-little\/\">Continue reading <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":7,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[450,354],"tags":[],"class_list":["post-356","post","type-post","status-publish","format-standard","hentry","category-dns","category-productivity"],"_links":{"self":[{"href":"https:\/\/blogs-new.it.ox.ac.uk\/networks\/wp-json\/wp\/v2\/posts\/356","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blogs-new.it.ox.ac.uk\/networks\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs-new.it.ox.ac.uk\/networks\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs-new.it.ox.ac.uk\/networks\/wp-json\/wp\/v2\/users\/7"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs-new.it.ox.ac.uk\/networks\/wp-json\/wp\/v2\/comments?post=356"}],"version-history":[{"count":5,"href":"https:\/\/blogs-new.it.ox.ac.uk\/networks\/wp-json\/wp\/v2\/posts\/356\/revisions"}],"predecessor-version":[{"id":361,"href":"https:\/\/blogs-new.it.ox.ac.uk\/networks\/wp-json\/wp\/v2\/posts\/356\/revisions\/361"}],"wp:attachment":[{"href":"https:\/\/blogs-new.it.ox.ac.uk\/networks\/wp-json\/wp\/v2\/media?parent=356"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs-new.it.ox.ac.uk\/networks\/wp-json\/wp\/v2\/categories?post=356"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs-new.it.ox.ac.uk\/networks\/wp-json\/wp\/v2\/tags?post=356"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}