Domain Authority is a 1 to 100 score Moz calculates to predict how well a domain might rank, based mostly on its link profile. Ahrefs (Domain Rating), Semrush (Authority Score), and others publish similar scores. They are handy for quick comparisons, but they are vendor models. Google has said it does not use any of them.
How these scores are built
Each vendor crawls the web, builds its own link index, and runs its own model. Moz's Domain Authority is trained to correlate with rankings it observes. Ahrefs' Domain Rating is based on the strength of a site's backlink profile. Semrush's Authority Score blends link data with traffic estimates and spam signals.
The scales are typically logarithmic, so moving from 20 to 30 is much easier than moving from 70 to 80. Scores also shift when the vendor updates its index or model, even if nothing changed on your site.
Google does not use them
Google has stated more than once that it does not use Domain Authority or any similar third-party score in ranking. Google has its own internal signals about sites and pages, and it does not share them. A rise or fall in a vendor's score tells you about the vendor's model, not about how Google sees your site.
Google has also been cautious about the idea of a single site-wide authority score at all, emphasizing that ranking happens page by page and query by query.
When these scores are useful
Used carefully, authority scores help with triage. They give a fast first pass when comparing link profiles, screening a long list of outreach targets, or spotting a site that is clearly larger or smaller than you.
- Comparing your link profile to competitors in the same tool
- Sorting outreach prospects before reviewing them by hand
- Tracking broad trends in your own link profile over time
When they mislead
Scores can be inflated by link schemes that the vendor's model does not catch, and a site with a modest score may be the most relevant publication in your niche. A link from a small, specialist site that your buyers read is often more valuable than one from a large general site with a higher number.
Example
Choosing between two outreach targets
An illustrative cybersecurity startup, Lockpane, is choosing where to pitch a guest article. One option is a general business site with a high authority score that publishes on every topic. The other is a smaller security engineering blog with a lower score, read by the exact people Lockpane sells to.
The team picks the security blog. The audience fit is better, the link is in context, and a reader who clicks through is a plausible buyer.
Common mistakes
Setting authority score targets as KPIs
A goal like “reach DA 50” rewards activity that moves a vendor's number, not activity that brings in qualified traffic or pipeline.
Buying links based on a seller's score
Link sellers often advertise high authority scores. Those placements break Google's spam policies whatever the score says.
Comparing scores across vendors
A Moz DA of 40 and an Ahrefs DR of 40 measure different things on different scales.
Questions
No. It is a score created by Moz. Google has said it does not use Domain Authority or similar third-party metrics.
It depends on your competitors. Compare your score to the sites ranking for your target searches in the same tool, rather than chasing an absolute number.
Common causes are lost links, the vendor recalculating its model, or other sites growing faster, since some scores are relative. It does not by itself mean anything changed in Google.
