When i get good traffic alexa rank going bad and when i get low traffic my traffic rank going good. why is this happening?
alexa ranking shows your traffic proportional to global traffic you may have low traffic but same day all world may have even lower traffic = your rank goes up because proportionally to daily total traffic you have higher rank end vv in addition on certain days more webmaster may be surfing and you may have more alexa toolbar user on site creating different result and vv as you know from careful reading of alexa pages - the ranking ONLY gives a reasonable value for rankings better than 100k the higher your ranking the more accurate your rank ( the higher the traffic = the better the accuracy ) if your traffic in the range or top 10k - (then alexa starts to become fairly accurate all times usually you get such organic rank when you have some 50'000 uv/day or more
Stop 10 people on the street ask them to name any search engine. How many "Alexa" responses do you think you'll get? Clearly why worry about it?
alexa does have a SE but is no SE but above all a website ranking system when you are in the top 40'000 or so then you will know why some webmaster care about alexa because based on your alexa rank you then may start to receive advertising requests from companies other than google adsense the OP here clearly was about alexa tank and NOT alexa search ...
I think alexa ranking can be boosted by adding toolbar etc. So just try to focus on your daily page visits rather than any other rankings.
Alexa algorithm is working in mysterious way. Don't hang over there for more time. Use google analytics only.