IP WHOIS
IPv4/IPv6 geolocation, ISP, ASN and reverse DNS. Leave blank to see your own IP.
What is IP WHOIS?
IP WHOIS lookup retrieves information about an IPv4 or IPv6 address: the country and city where it is located, which ISP owns it, its Autonomous System Number (ASN), and what reverse DNS returns. It is one of the most useful tools for network troubleshooting, spam investigation, and security research.
What is an ASN (Autonomous System Number)?
The internet is divided into Autonomous Systems — networks controlled by a single organisation (ISP, company,
university). Each AS has a unique number (e.g. AS15169 = Google). Knowing the ASN of an IP
lets you determine whether it belongs to a data centre, hosting provider, or residential ISP.
What is Reverse DNS (rDNS / PTR record)?
Regular DNS translates a domain → IP. Reverse DNS does the opposite: IP → domain. A mail server without a PTR record, or whose PTR does not match the sending domain, may be treated as a spam source.
When should I use this tool?
- Network troubleshooting: Identify where a connection is coming from.
- Spam/abuse investigation: See who owns a suspicious IP so you can report abuse.
- Security audit: Verify that your server IPs belong to your organisation.
- Geolocation: Understand where your visitors are connecting from.
How accurate is the geolocation?
IP geolocation is based on MaxMind GeoLite2 data and is accurate at the country level in ~95% of cases. Accuracy decreases at the city level. It cannot pinpoint a user's physical address — only the approximate area of their ISP.