title: Undefined reference errors in gcc
body: <p>gcc link results with errors:</p>
  
  <pre><code>dns.cpp: undefined reference to '__res_querydomain'
  dns.cpp: undefined reference to '__dn_skipname'    
  dns.cpp: undefined reference to '__dn_expand'
  dns.cpp: undefined reference to '__res_query'
  </code></pre>
  
  <p>Is there another library that I need to link to?</p>