Hi, I've heard the domain age is important to the ranking. Does it mean the oldest one can be the first though it has few back links for a targeted keyword? Is it useless to purchase a fresh domain name for a competitive keyword such as "web hosting"? Thank you!
yes, age plays an important role, all too often domains are abandoned within a years time and Google takes that into concideration Every single one of my active domains have done better with time (several years)
Domain age plays only a small role. Brand new sites out rank old sites every day. Getting high rankings is more about your link profile than any other one thing. Domain age is a site-wide ranking factor (it affects every URL on your site) so it is not going to carry a lot of weight. Not to mention it's only one of some 200+ ranking factors at Google. Web Hosting is a VERY competitive category. It's not impossible to rank, but you can plan on a long journey if your goal is to get to the top of the organic SERPs for that keyword phrase.
yes domain age is most important factor to be going visible on top in search engine but never means that only old domain name is enough to get in top 10, other parts also play important role such as rich content, keyword based domain, strong inbound links etc.