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Yes Anthony, Once I have contacted ahref support because of link difference in OSE and Ahref.com. They told, they provide more fresh data.

When you say improve your SEO do you mean improve your rankings?

The basic idea behind hub linking is that there are certain websites that are "hubs" for information - that is, they are one place that you can go to get resources on a topic.  A lot of times these domains link out a lot, because they want to showcase other websites that have good information resources on the topic.  They often do have good page authority, if they are good resources on the topic, because people link back to them. One thing to look out for when engaging someone to do Hub linking is, you want to make sure the sites you're getting links from are actually relevant resources that real people are using.  A lot of "hub" pages are created solely for SEO purposes and tend to have thin content and too many links, which can be a sign to Google that the link is a shady one.  So it's important to be judicious in selecting a hub page to target for links, and I would advise against trying to create one yourself unless you have a long-term strategy for how to continue adding content and making it useful.

Google's JohnMu confirmed that they ignore links from UpDowner. Barry Schwartz writes about it on Search Engine Roundtable at http://www.seroundtable.com/google-updowner-ignored-15369.html

I agree with this really people are obsessed with Page Rank and Domain Authority.....SEOr's need to get their head around the fact that traffic is what REALLY matters. What if you had a site with a DA of 100 but got no traffic? So OP what you need to really think about since you have started your seo campaign have you been able to increase your rankings and therefore have you been able to increase your traffic? Ignore D.A for now.......

Have you verified your website?