Definition
Referring Subnets count the number of unique Class C IP address blocks (the first three octets of the IPv4 address) among sites that point to your domain. This metric pushes diversity analysis further than Referring IPs: even if two sites have different IPs, if they share the same subnet (e.g., 192.168.1.x), they are probably hosted in the same datacenter or with the same host. Strong Referring Subnet diversity is a signal of link profile naturalness. Majestic in particular highlights this metric in its backlink analyses.
Key Points
- Measures diversity at the IP subnet level (Class C blocks)
- More granular than Referring IPs for detecting site networks
- Metric available in Majestic and some advanced Ahrefs reports
Practical Examples
Advanced PBN analysis
A site shows 150 Referring IPs but only 12 Referring Subnets. The IPs are different but concentrated on a few subnets, suggesting dedicated servers in the same datacenters for a site network.
Competitive benchmark
Comparing Referring Subnets of top 10 sites for a query, a consultant identifies that the best-ranked sites consistently have over 500 distinct referring subnets.
Frequently Asked Questions
Referring IPs count individual IP addresses, while Referring Subnets group IPs by subnet (Class C). Two IPs like 192.168.1.10 and 192.168.1.20 count as 2 IPs but a single subnet.
Google does not officially confirm using subnet diversity, but several patents and correlation studies suggest that network-level source diversity is a link quality factor.
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Last updated: 2026-02-07