Domain Authority is a score (on a 100-point scale) developed by Moz that predicts how well a website will rank on search engines. Use Domain Authority when comparing one site to another or tracking the “strength” of your website over time. This indicator is evaluated by combining all data of other Moz links – link to root domain, sum links, http://moz.com/learn/seo/mozrank, http://moz.com/learn/seo/moztrust… to the only scores.

To define DA, Moz “learned” Google algorithms and modelling the best way these search tools create the result table. Over 40 signals were integrated during calculation progress, which means your web Domain Authority will often change. Therefore, you had better use DA in competitive figure compared with other websites, not an exact measure for your internal SEO effort.
How to count Domain Authority score?
Moz counts DA basing on 100 score, logarithm base. Hence, increase of your score from 20 to 30 is much easier than from 70 to 80.
Domain Authority vs. Page Authority
While Domain Authority measures power, ranks by forecast from all domains or sub-domains, Page Authority evaluates power of sole pages. It is also true for other metrics like MozRank and MozTrust.
Where can you find Domain Authority?
DA metric is listed in tens of SEO and promotion platform in the internet. You can check out DA by using http://www.opensiteexplorer.org/ or http://moz.com/seo-toolbar – free SEO toolbar by Moz. Moz also combines metrics into all Moz Analytics campaigns, as well as API Mozscape.
How to improve Domain Authority?
Unlike other SEO metrics, it is so difficult to affect directly on Domain Authority. It originates from a metric synthesizing progress (MozRank, MozTrust, link profile,…) in which each component has an impact on score. This was carried on purpose. This metric reflects nearly accurately the competitive level in a defined position on Google.com.
The best way to change this metric is to improve your whole SEO ability. Particularly, you should focus on profile link – the most important one to MozRank and MozTrust – by using linking more to other quality websites.
Hope that the above information will partly help you to know about Domain Authority, how it affects on ranking in search engine result page.
Source: http://ecoupon.io/domain-authority-page-authority/

To define DA, Moz “learned” Google algorithms and modelling the best way these search tools create the result table. Over 40 signals were integrated during calculation progress, which means your web Domain Authority will often change. Therefore, you had better use DA in competitive figure compared with other websites, not an exact measure for your internal SEO effort.
How to count Domain Authority score?
Moz counts DA basing on 100 score, logarithm base. Hence, increase of your score from 20 to 30 is much easier than from 70 to 80.
Domain Authority vs. Page Authority
While Domain Authority measures power, ranks by forecast from all domains or sub-domains, Page Authority evaluates power of sole pages. It is also true for other metrics like MozRank and MozTrust.
Where can you find Domain Authority?
DA metric is listed in tens of SEO and promotion platform in the internet. You can check out DA by using http://www.opensiteexplorer.org/ or http://moz.com/seo-toolbar – free SEO toolbar by Moz. Moz also combines metrics into all Moz Analytics campaigns, as well as API Mozscape.
How to improve Domain Authority?
Unlike other SEO metrics, it is so difficult to affect directly on Domain Authority. It originates from a metric synthesizing progress (MozRank, MozTrust, link profile,…) in which each component has an impact on score. This was carried on purpose. This metric reflects nearly accurately the competitive level in a defined position on Google.com.
The best way to change this metric is to improve your whole SEO ability. Particularly, you should focus on profile link – the most important one to MozRank and MozTrust – by using linking more to other quality websites.
Hope that the above information will partly help you to know about Domain Authority, how it affects on ranking in search engine result page.
Source: http://ecoupon.io/domain-authority-page-authority/