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What is IP Reputation?

IP reputation is a score or classification assigned to an IP address based on its history of online behavior. Security systems use this data to decide whether traffic from a given address should be allowed, flagged, or blocked outright. 

Reputation is built over time through observed activity. Factors that negatively affect a score include sending spam, participating in denial-of-service attacks, distributing malware, or showing patterns consistent with bot traffic. Factors that support a positive reputation include consistent, low-risk behavior and no association with known threat lists. 

Email filters, firewalls, and content delivery networks all consult IP reputation data before accepting or routing traffic. A poor score can cause messages to be quarantined, connections to be refused, or requests to be rate-limited without the sender receiving any direct explanation. 

IP reputation data is maintained by a range of third-party services and threat intelligence providers, which means a single address may carry different scores across different systems.