Domain Authority 2.0 changed the measuring tool
Moz's guide places the calculation update in March 2019, after an earlier expansion of its link index. It explains that scores could rise or fall because of the new calculation. Domain Authority, often shortened to DA, is Moz's comparative score rather than a Google-issued grade. Moz guide to Domain Authority 2.0, March 2019
A score drop can create the wrong buying pressure
Imagine a monthly report shows a lower score and the first proposed response is a more expensive campaign. Before approving that spend, the buyer needs to know whether the website changed or the ruler changed. Those are different problems.
A vendor metric can be valuable for comparing similar sites. It becomes misleading when a single change is presented as proof that the business suddenly became weaker. The 2019 update is a concrete historical example of why the report needs context.
How we would read a changed authority score
We would put the score change beside the dates of the vendor's updates and the business's own results. Did qualified visits or inquiries change? Did comparable websites move at the same time? The aim is to understand the report before assigning a budget to fix it.
This does not make third-party scores worthless. It defines the job they can do. They help organize a comparison; they do not replace the outcome the business needs. The Moz Pro alternatives guide continues the buying discussion, while the Moz history shows how later brand metrics added another layer to the reports.
Sources for this milestone
Moz guide to Domain Authority 2.0, March 2019
Historical facts were checked November 2, 2026. The buying examples are our analysis, not claims made by the companies.