Advice and answers from the Ahrefs Team

There are at least two reasons why there can be more Referring IPs than Referring Domains.

First case:

The same domain can have multiple IP addresses. Usually, this is done to spread the load. More information: http://en.wikipedia.org/wiki/Round-robin_DNS

Second case:

Let's suppose, X is the domain for which there are only three backlinks from these pages:

 http://subdomain1.domain.com/index.html is located on the server with IP 1.1.1.1

 http://subdomain2.domain.com/index.html is located on the server with IP 2.2.2.2

 http://subdomain3.domain.com/index.html is located on the server with IP 3.3.3.3

It turns out that Domain X has only one referring domain (domain.com) but 3 referring IPs (1.1.1.1, 2.2.2.2, 3.3.3.3)

Did this answer your question?