How to link to root page

Hi,

what type of link is best?

1) hxxp://www.domain.com
2) hxxp://www.domain.com/
3) hxxp://domain.com
4) hxxp://domain.com/

I am starting a new site and I would like to finally do this right...

In the past I have usually used 1) or 3) for extrenal links. But for internal links, I use href="/" and that is probably conflicting, because it resembles 2) or 4). Also it also ocassionally happed to me that webmasters added the www when I used 3).

Please enlighten me,
V.

 

1) http://www.domain.com
2) http://www.domain.com/

 

I have to redirect http://www.sitename.com/ to http://www.sitename.com

?

 

http://www.sitename.com/ and http://www.sitename.com are the same

no, only this one http://domain.com to http://www.domain.com needs to redirect. but use 301.