Domain Authority

There are hundreds of ranking signals that Google accounts for in its SERPs that it’s impractical to try to improve a site’s SEO for every single one. Thankfully, SEO giant Moz came up with a metric that covers some of the major factors that search engines consider when ranking results.

Domain Authority (DA) is Moz’s predictor for how well a website will rank in the SERPs. It’s displayed as a score ranging from 1 to 100, where the bigger the number means the better the chances a website will have a high search ranking for all of its webpages. 

What Determines Domain Authority?

A website’s DA score is calculated through dozens of factors, including the total number of backlinks and the quality of the domains that link back to a website. 

For example, the BBC’s official website has a DA score of 95. This is no surprise, as the BBC is the national broadcasting organisation of the UK and a highly trusted news source with hundreds of thousands of backlinks to its domain coming from reputable websites.

By contrast, a website that has literally just been created starts with a DA score of 1, since it won’t have any backlinks at all and has no reputation to speak of. 

Domain authority scales logarithmically, meaning it’s easier to improve DA score when it’s on the lower end than it is when it’s on the higher end. A website can jump up from 1 to 30 in a relatively short amount of time, but it’s going to take a much bigger effort across a longer period to get the numbers to budge from 70 to 80. 

To see a website’s DA score, use Moz’s free domain SEO analysis tool.

Metrics of Domain Authority

To go a little bit deeper into how a website’s DA score is calculated, here are five of the most important metrics to consider:

  • Number and quality of backlinks — How many backlinks a website has and how relevant and authoritative those linking websites are.
  • Number and quality of external links — How many websites a website links out to and how relevant and authoritative those websites are.
  • Domain age — How long a website has existed. The older a website, the better its chances of ranking higher.
  • Domain registration information — Checks if the owner of a website also owns other websites. If even one website that is connected to an owner is considered spammy, the entire network can be negatively affected
  • Link diversity — How many backlinks from unique websites a website has. Websites with diverse backlink sources perform better.

Domain Authority vs Domain Rating

Another popular SEO metric that is similar to Domain Authority is Domain Rating (DR). It was created by search industry leader Ahrefs to sum up the quality of a website’s backlink profile. 

Like a DA score, a website’s DR is on a 100-point scale where the higher it is on the scale the likelier it is for a website to rank high in Google’s SERPs. The key difference is that Ahrefs developed DR mainly to evaluate a website’s backlink profile, not as a comprehensive valuation that includes all the other elements of a website to predict its search ranking, which is what Moz created DA for. 

DR being a good indicator for a website to rank high on Google is merely a consequence of a solid backlink profile weighing heavily into Google’s ranking algorithm.

To show a website’s DR, use Ahrefs’ Website Authority Checker.

Domain Authority vs PageRank

PageRank is a metric developed by Google to measure a website’s importance, taking into account the number of backlinks it has and the authority of the websites where those backlinks come from. 

A website’s PageRank was shown as a score ranging from 1 to 10 via Google’s PageRank Toolbar, with 10 being the highest score. Websites that had high PageRank scores would place above websites that had low PageRank scores in Google’s search results.

Google stopped updating and reporting on PageRank when they retired the PageRank Toolbar in 2016, so it is no longer visible to the public. There is no way for anyone outside of Google to know what any website’s PageRank is.

The original 1998 PageRank patent expired in 2018, but Google has been using a new algorithm that is somewhat similar to PageRank. In the updated system, ranking scores are based on the degrees of separation between “seed sites in trusted seed sets”, such as The New York Times website, and “non-seed pages”.

In lieu of a visible PageRank score, SEOs now use metrics like DA and DR to quickly qualify a website’s potential Google Search ranking.

Latest update on Moz’s DA

Domain Authority was a relatively stable metric for most of its lifetime which a vast majority of the SEO industry has depended on for site analysis, but Moz made significant changes to it in March 2019 as part of its Domain Authority 2.0 update:

  • Training Set — DA is now trained to better understand websites that don’t rank for any keywords.
  • Training Algorithm — DA now uses a neural network to better detect link manipulation among other benefits.
  • Model Factors — DA now has improved and better ranking factors, including Moz’s proprietary Spam Score and complex distributions of links based on quality and traffic
  • Link Index — DA now has a database of over 35 trillion links in Moz’s index.

Ultimately, the changes were made for DA to identify and remove spam, make better connections between websites, and be more responsive to Google’s algorithm updates.