What is the least important information when you analyze a public IP address in a security alert?

ARP (Address Resolution Protocol) resolves IP addresses to MAC addresses strictly within a local network segment and has no ability to interact with or return information about public IP addresses. Because a public IP is outside the local broadcast domain, an ARP request for it will never receive a response. Whois, DNS, and Geolocation are all capable of returning meaningful threat intelligence about a public IP, making ARP the only inapplicable option.

Whois queries return registration, ownership, and abuse contact information for a public IP block, which is directly useful in a security investigation.

Reverse DNS lookups on a public IP can reveal associated hostnames and infrastructure, providing valuable context during alert triage.

Geolocation maps a public IP to an approximate physical location and ASN, which helps analysts assess the geographic origin of a potential threat.