In many cases, webmasters redirect using HTTP the main domain to another, this makes that most of search engines cannot index the web correctly.

For a well done SEO job, it is recommended not to use redirections. This way, it is easier for the web crawlers and most of them will index the site easily.

It is important to mention, that the HTTP specifies that any URL should include the protocol, that means that not including the protocol can make it difficult to search engines to crawl.