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Hi snjaoieiw, To get a detailed answer from Moz staff on what DA is, you might consider searching the Q&A forum. In short, though, it is a Moz metric (not a Google or Bing metric) that takes into consideration the number (and quality) of backlinks your website has. That said, have you been working on building up high quality backlinks? -Zack

Hi Uzair, As far as I know, the different tools such as Moz actually use different data sets. They aren't looking  at the complete picture, in other words. They do have very large amounts of data, and are very useful if used correctly, but somewhat different from one another, and aren't infallible. Hope this helps! Zack