1. Known as a Canonical URL issue. One is a relative URL and one is the Absolute URL (
http://www.yourdomain.com). Google sees all different forms of a URL as separate sites. IE. www. - http:// - http : //www (spaces added to stop hyperlinking)
When this happens it dilutes your PageRank since the
PR is spread to our various canonical URLs
2. Yes depending on server Unix box = Apache Mod Rewrite Windoze = Isapi
3. See # 1 Answer above
4. Yes Google will index various URL forms of your site.
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