defaria.com/blogs/General/archives/000722.html

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  15    <title>General: Broken DNS</title>
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  57                      <a id="a000722"></a>
  58                      <div class="entry" id="entry-722">
  59                         <h3 class="entry-header">Broken DNS</h3>
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  62                               <p>This seems to be the trend now a days in Corporate IT. Is it just Windows related? I don't know. It used to be that you could rely on DNS. Now you can't. Case in point - people hear talk about a machine known as "seacase". Others use the name usseacase. Whicih is correct? Well an educated guess would be they are one in the same and a DNS alias exists between them. IOW seacase is just a "pretty" name for usseacase.</p>
  63
  64 <p>Now I used to be that you could verify that with DNS, in particular you could use nslookup to find each of the names and see they have the same IP address. But more and more, Corporate IT DNS stuff is screwed up, perhaps in the name of security, such that they don't always resolve:</p>
  65
  66 <div class=code>$ nslookup usseacase
  67 Non-authoritative answer:
  68 Server:  &lt;dns server>
  69 Address:  13.230.100.200
  70
  71 <p>Name:    usseacase.&lt;domain>.com<br />
  72 Address:  13.230.100.74<br />
  73 </div></p>
  74
  75 <p>So we can look that one up but we can't lookup the other:</p>
  76
  77 <div class=code>$ nslookup seacase
  78 *** &lt;dns server> can't find seacase: Non-existent domain
  79 Server:  &lt;dns server>
  80 Address:  13.230.100.200
  81 </div>
  82
  83 <p>However ping works! And verifies that this is the same machine. So why doesn't DNS know about this?</p>
  84
  85 <div class=code>$ ping seacase
  86 PING seacase (13.230.100.74): 56 data bytes
  87 64 bytes from 13.230.100.74: icmp_seq=0 ttl=127 time=230 ms
  88 64 bytes from 13.230.100.74: icmp_seq=1 ttl=127 time=0 ms
  89
  90 <p>----seacase PING Statistics----<br />
  91 2 packets transmitted, 2 packets received, 0.0% packet loss<br />
  92 round-trip (ms)  min/avg/max/med = 0/115/230/115<br />
  93 </div></p>
  94
  95 <p>Another pet peave of mine is people using either IP addresses instead of names (Do you refer to your friends by their cell phone numbers?) or using fully qualified machine names all the time when you don't need to...</p>
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 102                            <span class="post-footers">Posted by
 103                            Andrew DeFaria on
 104                            March  1, 2010 11:48 AM</span> <span
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 241                               href="http://defaria.com/blogs/General/archives/000745.html">Point people more directly</a></li>
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 247                               href="http://defaria.com/blogs/General/archives/000736.html">How not to run a company</a></li>
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 249                               href="http://defaria.com/blogs/General/archives/000734.html">How to get your mic working on Ubuntu 9.10</a></li>
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 251                               href="http://defaria.com/blogs/General/archives/000729.html">Cell phones - Not up to snuff!</a></li>
 252                                                          <li class="module-list-item"><a
 253                               href="http://defaria.com/blogs/General/archives/000728.html">Stupid is as stupid does</a></li>
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 255                               href="http://defaria.com/blogs/General/archives/000723.html">Priority Queues...</a></li>
 256                                                          <li class="module-list-item"><a
 257                               href="http://defaria.com/blogs/General/archives/000722.html">Broken DNS</a></li>
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