Plato reports a saying of Protagoras: man is the measure of all things. The line was about people, but it describes SEO scores well. Ahrefs, Moz and Semrush each built their own ruler, and each one is the measure of its own results.
So the same domain can read DR 52 in one tool and Authority Score 5 in another. A Reddit poster reported exactly that gap on an expired domain, and metric trust came up in several of the buyer threads we read. The first search results for the question are blogs by agencies and SEO vendors. In this post we go to the vendors' own help pages and to Google, and we opened each of them on 19 October 2026.
We sell aged domains, so you should know where this lands. None of these numbers is a verdict, ours included.
Three scores, three different recipes
| Score | Maker | What goes into it | Scale |
|---|---|---|---|
| DR (Domain Rating) | Ahrefs | Backlinks only. Nofollow links are ignored. A linking site splits its rating among the domains it links to. | A 100-point scale, compared with the rest of the Ahrefs database |
| DA (Domain Authority) | Moz | A machine-learning model built mostly on links from the Link Explorer index. Since March 2019 it is a neural network that also folds in Spam Score and the spread of link quality. | 1 to 100, new sites start at 1 |
| Authority Score (AS) | Semrush | Link power, modelled organic traffic and six spam checks. | 1 to 100 |
Three things follow from the table.
- The inputs differ. DR looks only at links. AS also reads an estimate of organic traffic, and Semrush says that estimate comes from its own keyword positions. DA adds Moz's own spam model.
- The crawlers differ. Moz says each link index builds "a slightly different picture of the web". Majestic says that even with identical counting methods, index sizes may still vary because indexes capture different time windows.
- The clocks differ. Ahrefs says a full refresh of its database takes about two months. Moz says it tries to recrawl high-quality pages at least every 90 days. Semrush recalculates Authority Score every two weeks. Two tools can be looking at different weeks of the same domain's life.
All three scores are also relative. Ahrefs explains that a DR 100 site cannot become DR 101, so when others gain links, you can slide with no change to your own. Moz says the same about DA and notes that a model update can move it too.
What Google says about these scores
Google does not use any of them. In its March 2024 spam policy post, Google says third-party authority scores "don't correspond to any of Google's own signals nor come from Google". The same post says Google's ranking works mainly at the page level, with some site-wide signals. In a 2016 hangout, John Mueller said that from his point of view Google does not have anything like a website authority score. He went on to talk about site-wide quality signals. We read this from auto-generated captions, so treat the wording as approximate.
The vendors agree. Ahrefs writes that DR is not a Google ranking factor. Moz writes that Domain Authority is not a Google ranking factor. Semrush says Authority Score "is not a metric used or provided by Google", though that sentence sits on its enterprise data page and not in the help article.
Ahrefs does say DR correlates with rankings "pretty well", less well than its page-level score. A correlation is a hint about where strong links tend to sit. It is not a signal Google reads.
Why an aged domain can look odd in one tool
An aged or expired domain is where these recipes clash most.
- Ahrefs crawls by popularity. Its help page says less popular domains are only partly crawled, and crawl priority follows DR and UR. If a tool crawls a domain only in part, its score rests on what the tool has seen.
- Semrush runs spam checks that hit aftermarket domains. Among them: no rankings in Google's top 100, more than 90% dofollow referring domains, many referring domains on the same IP, and a backlink profile that overlaps 95% or more with another domain. A domain with no organic rankings, or with a profile that matches another domain, trips these checks. Semrush does not say how often that happens with aftermarket domains.
- Moz says DA itself was gamed. In its 2019 analysis, Moz wrote that DA "has itself been targeted for spam" and that domains were sold on it. It reported that its new model cut the average DA of the auction-domain test sets sharply, by about 61% for "high-quality" auction domains and nearly 95% for "mid-quality" ones. That is Moz's own test from 2019, not an independent audit.
- Ahrefs has no spam score. Its help center says it does not offer one, and that a low DR does not mean a site is spammy.
- Moz Spam Score is a correlation. It is the share of similar sites that Google has penalized, from 27 features, updated quarterly, and Moz itself says it shows correlation, not cause.
Semrush calls its score "hard to manipulate", which is a marketing claim. We found no vendor statement saying its score is unreliable for expired domains. Our reading of Moz's account is that a score people pay for becomes a target. The vendors do not hide the limits: Ahrefs tells readers to never judge a site on site-wide authority alone.
Google's view of expired domains has nothing to do with scores. Its spam policies call it expired domain abuse when someone buys an expired domain mainly to manipulate rankings with content that gives users little value. In the same March 2024 post, Google says it is fine to use an old domain name for a new, original site made for people. The test is intent and content, so a high number does not protect you from the policy.
What to check besides the number
Aristotle, early in the Nicomachean Ethics, says an educated person looks for as much precision as the subject allows and no more. This is a paraphrase, not a quotation, and the passage is about ethics and not SEO. A domain score gives one tidy whole number for something no vendor can measure exactly.
- Open the history. Look at what the domain published before, using the Wayback Machine. Our guide to how to check an aged domain before you buy it covers the steps.
- Read the links, not the total. Look at the referring domains in the tool you trust and ask whether real sites would link to them. Count the pages that link, and look at the anchor text.
- Compare two tools. If DR and AS differ a lot, find out why. A gap tells you where to look, such as a recent change or an under-crawled profile.
- Treat traffic estimates as estimates. Semrush says its traffic figure is modelled from its own keyword data, and other tools do the same.
- Look at the date. Every number has a date. A score checked months ago may not match what the tool shows now.
If you are new to the terms, expired vs aged domain: which to buy explains the difference.
How we show numbers at SerpYard
SerpYard has just started, and we are careful about what we claim. We type DA, PA, DR, UR and spam score into each listing by hand from free toolbars, and we show the date we checked them. The numbers can be stale or wrong, and free toolbars have limits. Different tools will give you different figures, which is the point of this post. For backlink offers whose source site we mask, we show ranges and not single values. We do not call any stock vetted.
You can browse the aged domains we list and run your own checks on the domain names, which are public.
Seneca wrote that we suffer more in imagination than in reality. A score is a number you imagine meaning something. Check the thing it points to.
Frequently asked questions
Why is my DR different from my DA?
They use different inputs, different crawls and different update times. DR counts links only. DA is a machine-learning model that also uses spam and link-quality signals. Neither is a Google metric.
Which score should I trust: DR, DA or Authority Score?
None of the vendors tells you to trust one alone. Ahrefs says DR is not a measure of legitimacy, Moz says its Spam Score shows correlation, and Semrush says Authority Score is best used to compare domains. Use them to compare, then check the history and links.
Does Google use Domain Authority?
Google does not say it does. Its March 2024 post says third-party authority scores do not correspond to any of its signals. Moz also says DA is not a Google ranking factor.
Can an expired domain have a fake DA or DR?
Moz said in 2019 that DA was targeted for spam. We found no vendor statement about expired domains in particular. A score can reflect a link profile you would not want, so read the links.
Does a high score mean a domain is safe to buy?
No. Google's expired domain policy is about intent and content, and it does not mention scores. Semrush adds that Google penalties are "highly unlikely" to show in its score, so a clean number tells you nothing about that.