title: Expected 'trust-anchor' error message when install Bind DNS Server on Centos 5.9
body: <p>I'm about installing DNS Server on VPS with Centos 5.9 operating system, I have followed step by step from this website <a href="https://www.digitalocean.com/community/articles/how-to-install-the-bind-dns-server-on-centos-6" rel="nofollow">https://www.digitalocean.com/community/articles/how-to-install-the-bind-dns-server-on-centos-6</a></p>
  
  <p>when i try to restart the service with: </p>
  
  <pre><code>    service named restart 
  </code></pre>
  
  <p>there is following error:</p>
  
  <pre><code>Stopping named: [ OK ] 
  Starting named: 
  Error in named configuration:
  
  /etc/named.conf:23: unknown option 'dnssec-validation' 
  /etc/named.conf:24: expected 'trust-anchor' near ';'
  </code></pre>
  
  <p>any solution to solve this problem? Thank you very much.</p>