Think of it as the internet's version of a "postal code" for a large network.
This unique number is assigned to a large group of IP addresses all operated by a single entity, such as:
They allow these large, independent networks to announce their presence and efficiently exchange data with each other, forming the backbone of the internet.
While a fraudster can easily change their individual IP address, it is much harder for them to change their entire network provider (the ASN).
This provides several key advantages:
Identifying Bad Neighborhoods: Certain ASNs, particularly those belonging to data centers or hosting providers known for lax security, are notorious sources of bot traffic.
Detecting Coordinated Attacks: If we see a pattern of suspicious clicks coming from many different IP addresses, but they all resolve to the same ASN, it's a strong signal of a large-scale bot attack originating from that single network.
Durable, Proactive Blocking: Blocking an entire malicious ASN is a much broader and more effective form of protection than blocking constantly changing IP addresses one by one.
In summary, analyzing the ASN allows us to move beyond chasing single IPs and instead identify and block entire malicious networks, providing a more robust and scalable defense against click fraud.