One of the clearest changes in Ahrefs DR4 is that subdomains can now receive their own Domain Rating. A blog at blog.example.com, a documentation portal at docs.example.com, and the root example.com can have distinct scores based on the links pointing to each host.
This matters for SaaS companies, developer tools, hosted websites, and anyone measuring link opportunities from subdomain-based publications. For the other changes in the new model, see Ahrefs DR4 explained.
How DR3 treated many subdomains
Under the previous model, Ahrefs often showed a subdomain with the same DR as the parent root domain. This could make an individual project hosted on a popular website builder appear to have a backlink profile comparable to the platform itself.
Ahrefs says there were some exceptions, so “all subdomains inherited DR3” would be an inaccurate generalization. Nonetheless, inherited ratings were common enough that the company specifically addressed them in its DR4 announcement.
What DR4 changes
DR4 evaluates a subdomain's own backlink profile. A small hosted blog with very few independent links will not simply borrow the platform's authority score. An established documentation portal that attracts references from many relevant sites may retain a strong score.
For instance, Ahrefs' November 5 announcement showed that help.ahrefs.com now has its own score, separate from the Ahrefs root domain. The reported preview numbers can change over time as the index is updated.
An important nuance: this is a change to Ahrefs' measurement, not a new Google instruction to avoid subdomains. A subdomain may be the right technical choice for isolation, documentation, a community, or hosted infrastructure.
Examples of affected website types
Hosted projects and portfolio sites
Projects on website builders or shared hosting platforms should check their individual hostname. The DR of the root platform is not a reliable proxy for the project's links.
SaaS documentation and help centers
Support articles often earn backlinks independently. Under DR4, a help-center subdomain may be better evaluated on references to its actual technical content instead of the marketing site alone.
Blogs and community portals
Companies using blog.company.com or community.company.com should monitor those hosts directly, especially when evaluating guest posts, partnerships, and outreach opportunities.
GitHub Pages and other developer sites
Do not assume project.github.io inherits the rating of github.io. Assess the project's own links and audience.
Should you move your blog to a subfolder?
Not solely because DR4 changed. Moving a site from a subdomain to a subfolder is a real architecture migration. It can involve redirects, canonical URLs, internal links, analytics configuration, hosting, and temporary search volatility.
DR4 does not establish that Google ranks all subfolders better than all subdomains. Evaluate a migration using your content strategy, technical needs, actual organic performance, and maintenance costs—not a single third-party metric.
How to audit subdomain performance
- List root and subdomain hostnames you operate.
- Check DR4 for each exact hostname through a reputable Ahrefs-powered checker.
- Review which editorial pages on each host earn citations and links.
- Use Search Console properties and filters appropriate to the host or URL scope you want to assess.
- Compare actual search traffic and engagement separately from DR.
- Record your architecture and model version in future reports.
The IndieTools Domain Rating checker rates the exact hostname you enter, so you can check a subdomain's DR3 and DR4 side by side. If a subdomain's score fell, the DR4 drop diagnosis guide helps separate the model change from a real link problem.
Frequently asked questions
Do subdomains always have lower DR4 than their root domain?
No. Scores depend on their respective backlink profiles. There is no universal fixed difference.
Does DR4 mean Google treats subdomains as separate sites?
No. Ahrefs' scoring decision should not be confused with a statement about all Google indexing or ranking behavior.
What if my blog's DR4 is zero?
A numeric zero is a possible Ahrefs result; it does not prove the blog is spam or that no one visits it. Confirm the exact hostname and data availability; the guide to checking DR4 for free explains how a zero differs from an unavailable score.
Sources and further reading
- Ahrefs: DR4 and independent subdomain scores
- Ahrefs: Free Domain Rating API
- Ahrefs Help: What is Domain Rating?
Last fact-checked: November 6, 2026.
