Free IP lookup: resolve IP to ASN and organization
IP lookup vs WHOIS lookup
IP lookup answers "which network announces this address?" using BGP routing data. WHOIS adds allocation history, abuse contacts, and registrar-style fields from the RIR. For incident triage, start with IP lookup for speed; drill into IP WHOIS when you need contacts or registration dates.
Read how to read WHOIS output for field-by-field reference.
Common use cases
Firewall log triage
Identify the ASN behind suspicious traffic quickly.
CDN and cloud debugging
Confirm which provider announces an edge IP.
Bulk investigations
Pair with bulk WHOIS for mixed IP and domain lists.
SPF and sending IP validation
Map sending IPs to providers after SPF expansion.