A lot of people argue that parking a domain so that it loads your main website but through the parked domain is bad for SEO because it ends up being duplicate content (defines two paths for the search engine to reach the same content). Can someone confirm if that is true? If I have: domain1.com domain1.ca domain1.net and they all go to the same website, would that hurt my PR/SERP's? Is it better to 301 redirect the extra domains to the MAIN website domain? Also, is it possible to rank those 301 redirect domains considering the fact that Google takes that domain as permanently moved to a new address? Thanks!
yes it's right that parked domains hurt website ranking. Because many parked domain show same content at a time.
I figured just as much that's why I've set up all my domains to 301 redirect for the moment until I can figure out a use for them.