What is domain rating?
A domain rating is a metric developed to help predict how likely a domain, subdomain, or page is to rank in search engine result pages (SERP). This website ranking measure is determined on a logarithmic scale and the score ranges from 1 to 100, 1 being where all new websites start and move on up from there.
Although we don't know the exact algorithm of ahrefs' domain rating, it is calculated by looking at multiple important factors, including referring domain, linking root domains, and the total number of links, into a single DR score.
Whereas a website's domain rating measures the strength of a website there is also a DR score attributed to each web page, called page authority or page rank.