What are Referring Domains? And Why They Matter More Than Total Backlinks

When you start analyzing expired domains, you'll see two closely related metrics: Backlinks and Referring Domains. A domain might have 50,000 backlinks but only 200 referring domains. Another might have 1,000 backlinks from 500 referring domains. To a beginner, the first domain looks far more powerful. But in the eyes of Google, the second domain is almost always the more valuable and authoritative asset.

This distinction is one of the most fundamental concepts in off-page SEO. Understanding why the number of unique referring domains is more important than the total number of backlinks will completely change how you evaluate an expired domain's quality. Let's clarify the difference and explore why diversity is king.

Defining the Terms

First, let's get the definitions straight.

• Backlinks: This is the total count of all individual hyperlinks from other websites that point to your domain. If one website links to you 100 times from 100 different pages, that counts as 100 backlinks.
• Referring Domains: This is the total count of unique websites (or root domains) from which you have at least one backlink. If one website links to you 100 times, that still only counts as 1 referring domain.

The "Vote of Confidence" Analogy

The easiest way to understand the difference in value is with a simple analogy. Think of links as votes in an election.

Scenario A: One person stands up and shouts your name 1,000 times. This is equivalent to **1,000 backlinks from 1 referring domain.** This is loud, but is it influential? It shows strong support from one single source, but it's not a broad consensus.

Scenario B: 500 different people each stand up and say your name once. This is equivalent to **500 backlinks from 500 referring domains.** This is a powerful demonstration of widespread support and trust from many independent sources.

Google's algorithm thinks much more like Scenario B. It sees links from unique, independent domains as separate "votes of confidence." The more unique domains that vote for you, the more trustworthy and authoritative your site appears to be. While subsequent links from a domain that has already linked to you still have some value, they have diminishing returns. The first link from a new, high-quality domain is by far the most powerful.

[Image showing a diagram comparing 1000 backlinks from 1 RD vs. 500 backlinks from 500 RDs]

What a High Backlink-to-Referring-Domain Ratio Can Signal

When you see an expired domain with a very high number of backlinks but a low number of referring domains, it's often a red flag for unnatural link-building tactics.

• Sitewide Links: This is the most common cause. The previous owner may have gotten a link placed in the footer or sidebar of a blog. This means that every single page on that blog (potentially thousands of pages) links back to the domain. This results in a huge backlink count from a single referring domain. Google is very good at identifying and devaluing these types of sitewide links.
• Blog Comment or Forum Spam: Another cause could be automated software that spammed the domain's link across thousands of pages on a single forum or blog.

A healthy, natural backlink profile, on the other hand, will have a much more balanced ratio. It will show links acquired over time from a wide and diverse set of websites within its niche.

How to Use This in Your Evaluation

When you're looking at a list of domains on Unowna, don't be instantly drawn to the one with the highest backlink count. Instead, make the "Referring Domains" column your primary focus. A domain with 800 referring domains is almost always a stronger starting point than one with 100 referring domains, even if the second one has more total backlinks.

When you're setting filters, consider adding a minimum threshold for referring domains (e.g., must have more than 50 RDs). This is a great way to filter out domains that might have an artificially inflated backlink count from a few low-quality sources. Your goal is to find a domain with a broad and diverse base of support, as this is what signals a truly authoritative and resilient asset.

Conclusion: Prioritize Diversity

In the complex world of SEO, not all metrics are created equal. Total backlinks can be a vanity metric, easily manipulated and often misleading. The number of unique referring domains, however, is a much more honest and powerful indicator of a domain's true authority and trust on the web.

When you evaluate your next expired domain, train your eye to focus on the diversity of the link profile, not just the volume. By prioritizing referring domains, you'll be much better equipped to identify the domains that have earned genuine, widespread credibility—the kind of authority that Google truly rewards.