IP Address Lookup
Look up any public IPv4 or IPv6 address: reverse DNS (PTR), location, ISP, ASN, and forward-confirmed reverse DNS.
When IP enrichment runs after a visitor requests details or submits an IP lookup, the IP being looked up is sent to ipwho.is to retrieve ISP, ASN, and location metadata unless request headers already provide the needed visitor network details.
What This Tool Does
Our IP address lookup checks any public IPv4 or IPv6 address and returns reverse DNS (PTR hostnames), forward-confirmed reverse DNS, approximate location, ISP, ASN, and related network context. Use it for IP address lookup, reverse DNS lookup, email PTR checks, and quick network investigation—without a separate reverse DNS tool.
Common Use Cases
- Run an IP address lookup for location, ISP, and ASN details
- Perform a reverse DNS lookup (PTR) for any public IP
- Verify email server PTR and forward-confirmed reverse DNS configuration
- Identify the hostname behind an IP address from your logs
- Verify the location of a suspicious IP accessing your server
- Check which ISP and network block owns an IP range
- Investigate the origin of spam or malicious traffic
- Confirm your own public IP address and location data
Frequently Asked Questions
What is reverse DNS lookup?
Reverse DNS lookup (rDNS) maps an IP address to a hostname using a PTR record. Enter a public IP on this page to see PTR hostnames and whether forward DNS confirms them (forward-confirmed reverse DNS).
How do I look up reverse DNS for an IP?
Use this IP address lookup: enter a public IPv4 or IPv6 address and run the lookup. Results include reverse DNS (PTR) hostnames when they exist, plus location, ISP, and ASN context on the same page.
How accurate is IP geolocation?
IP geolocation is typically accurate at the country and city level (80-95% accuracy), but cannot pinpoint exact street addresses. Mobile IPs and VPNs may show incorrect locations. ISP and ASN data is highly accurate as it comes from official registry records.
Can I look up any IP address?
Yes, you can look up any valid public IPv4 or IPv6 address. Private IP addresses (like 192.168.x.x or 10.x.x.x) cannot be geolocated as they are not routable on the internet.
What is an ASN (Autonomous System Number)?
An ASN is a unique identifier assigned to networks (like ISPs or large organizations) that participate in internet routing. It helps identify who manages a particular IP address block.
Why is reverse DNS important for email?
Many email servers check that the sending IP has forward-confirmed reverse DNS: the PTR hostname resolves back to the same IP. Missing or mismatched PTR records often cause emails to be marked as spam or rejected entirely.
Why doesn't my IP have a reverse DNS record?
PTR records must be set up by whoever controls the IP address—usually your ISP or hosting provider. Many residential ISPs don't configure reverse DNS by default. Contact your provider to request PTR record setup.
Can I set my own reverse DNS?
Only the owner of the IP address block can set PTR records. For most users, this means contacting your ISP or hosting provider. Cloud providers like AWS, Azure, and GCP allow you to configure reverse DNS through their control panels.