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Hi - Thanks for posting. Domain Authority is a proprietary Moz metric and should be consistent across all Moz offerings. In terms of improving your Domain Authority, with the information above in mind, it's best to look at both your on-page SEO to make sure you've covered the basics. Then you also want to look at your off-site SEO and building more links to your site. There are lots of different areas of Link Building to explore, from patching up broken links, improving your internal link profile, and content creation. Here is a great video by our founder Rand which goes over some easy link building tactics to get you started.

Google bot can read any URL that is viewable by itself. Try this: copy the URL of the complete transaction page and paste it in fresh broweser where your website is not cached/cookied there. If you can see the page - So google can! For your "discount for a link" concern - I need to know more details.