title: Block CNAME redirect from a domain I don't own
body: <p>Someone has registered a domain and is using a CNAME redirect to direct traffic to my site. Google is seeing this as duplicate content and it's affecting my rankings.</p>
  
  <p>Is there anyway of blocking access for traffic that comes to my site through the domainnotundermycontrol.com redirect?</p>
  
  <p>Thanks in advance.</p>