Does 301 redirect really work?

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

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  Sam “H” Mah: Recently I purchased the old domain and wanted to do a redirecting 301 back to my client's site. ; Does 301 redirct really work in this case? Where to put the .htaccess file? ;
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  Vinay Trivedi: First you need to check your old domain history in wayback machine. Yes in htacess file you need to place the 301 redirection. One of ftp to place your root directory your client data. And make sure in terms of seo page to page redirection required. It's depend open the histroy of domian. 
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  Jim Munro: Hi +Sam Mah. I think +Vinay Trivedi has given good advice. If the old domain has any past sins which might have led to penalties, the bad karma will be poured onto your existing site. The wayback machine is as good as any to investigate an old domain.
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  Sam “H” Mah: +Vinay Trivedi +Jim Munro ; Yes I understood that background check ; is necessary. ; If I use .htaccess, what is the exact code for this? Thanks guys
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  On Page Assistant: redirect 301 /old/old.htm http://www.you.com/new.htm 
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  Vinay Trivedi: +Sam Mah​ Rewriterule ^oldurl.html$ http://www.newurl.html [R=301, L]
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  Sam “H” Mah: +Vinay Trivedi ; Why the .html extension? I don't get it.
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  Edwin Jonk: From the expert panel in this week's SEO Questions hangout on air on 00:25:40 into the YouTube video: https://dumbseoquestions.com/q/does_301_redirect_really_work +Sam Mah
  
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  Sanjay Upadhyay: +Sam Mah ; Hey buddy can u tell me what is the benifit of purchased old domain and redirect them to my main site?
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  Sam “H” Mah: +Sanjay Upadhyay Acquire backlink juice and referral traffic to your main site
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  Sanjay Upadhyay: i think getting maximum number of  ;back links from different class of IP Address is good. But In that case you get a link from your old domain that is high in authority PR too. (i know pr doesn't matter more now a days) only one time . Because next time when you will get backlink from same domain that has same "IP Address" does it effect on ranking. ;
  
  Now investing time and money both for a single "IP Address" link may be costly as compare to other activities of Link Building what do you think +Sam Mah ;
  
  Even Guest Blogging on High Authority News or Government site also effect same.  ;Very Soon I'll share a case study of mine how i boost my rank with guest blogging on new site. My was position was 25 and after Guest Blogging i jumped over 13 position.
  
  what you say +Sam Mah ;
  
  Thanks
   ; ;