Alias domain ranks higher than the main domai

Selected answers from the Dumb SEO Questions Facebook & G+ community.

• 
  Luke Pilkinton-Ching: I've got a website where the alias domain has started to rank higher than the main domain in the last 2 days.  ;And the main domain has dropped.  ;
  
  What to do?  ;
• 
  Jim Munro: Hi Luke, thank you for your participation here. Please let us look more closely at your site with a url added like this: yourdomain(dot)com.
  
  At first glance, if I understand what you are asking, I think you should 301 the alias domain to the actual domain in case there are links out there pointing to the alias.
• 
  Luke Pilkinton-Ching: Hi Jim.  ;Thanks for your reply.  ;
  Yes, that's what I thought.  ;Just in the .htaccess file? ;
• 
  Jim Munro: That should work, Luke, but I'd wait for someone like +Dave Elliott ;to confirm before embarking on any path.
• 
  Luke Pilkinton-Ching: Understood.  ;Thank again.  ;I'll wait to hear from Dave or the like.  ;
• 
  Dave Elliott: Id also canonicalise and submit a sitemap via google search console with the correct domains.. Depending on the cms you might not need to do it via an htaccess file for example in wordpess you can set the primary domain via the 'domains' section of your admin area.
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  Luke Pilkinton-Ching: Hi Dave.  ;Thanks for your comment/confirmation.
  
  I'm using Joomla.  ;Can you point me in the right direction to a tutorial of how canonicalise a domain name through a sitemap.xml
  
  Luke
• 
  Edwin Jonk: From the expert panel in this weeks SEO Questions hangout on air on 00:45:31 into the YouTube video: https://dumbseoquestions.com/q/alias_domain_ranks_higher_than_the_main_domain +Luke Pilkinton-Ching
  
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