title: Avoiding Duplicate Content from Search Engines when multiple domain names display the same website
body: <p>I am trying to sort out how to properly display one web site on multiple domains.</p>
  
  <p>Given:</p>
  
  <p>1 Webserver with 1 IP address. (1.1.1.1)</p>
  
  <p>100 different domain names. (example.com, example.net, example.co, example.biz, etc.)</p>
  
  <p>I would like all 100 domain names to display the content that is served from the 1 webserver.</p>
  
  <p>It seems to me that the most efficient method to achieve this is to use the DNS, as follows:</p>
  
  <p>example.com zone file</p>
  
  <pre><code>$ORIGIN example.com.
  @ in A 1.1.1.1
  *.example.com. in CNAME @
  </code></pre>
  
  <p>example.net zone file</p>
  
  <pre><code>$ORIGIN example.net.
  *.example.net. in CNAME example.com
  </code></pre>
  
  <p>example.co zone file</p>
  
  <pre><code>$ORIGIN example.co.
  *.example.co. in CNAME example.com
  </code></pre>
  
  <p>etc. (other DNS records only omitted from the above example for brevity, ie. SOA)</p>
  
  <p>None of the domains have ever been used before, so there are no rankings for them.</p>
  
  <p>It seems to me that using a 301 redirect would introduce a significant amount of server and maintenance overhead.  Each domain would, in effect, need to be hosted 'individually' for this and each would need an ip address (could be a shared IP).</p>
  
  <p>With the above example, would a Search Engine consider the content that is returned by the 1 webserver, to each domain, to be Duplicate Content?  Or are Search Engines clever enough to know that although the domain name is different, the IP address is the same for all the content, and know that it only got that content after having resolved the CNAME lookup?</p>