What is CGNAT (Carrier-Grade NAT)?
Also: carrier-grade nat · carrier grade nat
CGNAT, or carrier-grade NAT, lets an ISP share one public IP among many subscribers by assigning them addresses in the 100.64.0.0/10 range. Common on mobile and some fibre networks, it means many users appear to come from the same public IP, which can trigger shared-reputation false positives.
Addresses in 100.64.0.0/10 (RFC 6598) are not publicly routable — they exist only between the subscriber and the ISP's NAT. The public IP a CGNAT user shares is a real ISP address, but it may carry the combined reputation of hundreds of users.
CGNAT is why a clean mobile user can occasionally be flagged: another subscriber behind the same public IP may have triggered abuse signals.
How IPLogs handles it
IPLogs recognizes 100.64.0.0/10 as carrier-grade NAT and explains it on the per-IP page rather than treating it as a routable address.
Why is my IP flagged?