Let me first explain Domain Authority Briefly.
Domain Authority is a Moz score that decides your website ranking on search engines. It is calculated on a 100- point scale. The nearer to 100, the better it is . DA of 30+ is meant your website hold an authority in SERP.
It is calculated by summing up other metrics like Root Domains, Total Links, Moz Trust, Moz Rank etc all together.
Increasing Domain Authority is a tedious task but worthy. Below listed are few effective ways to improve Domain Authority of your website .