Reverse DNS lookup
Find the reverse DNS name (PTR record) for an IP address, or for a whole list of them. Useful for checking mail servers, customer routers and the names your network shows in traceroutes.
Lookups go to Cloudflare's public DNS (1.1.1.1). Nothing is sent to Helpnyx.
How to use it
Three steps
- Enter addresses. One per line, IPv4 or IPv6. Up to 100 at a time.
- Look up. Each address is turned into its reverse name (for example 8.8.8.8 becomes 8.8.8.8.in-addr.arpa) and asked for a PTR record.
- Check FCrDNS if needed. Mail servers also need the name to point back to the same address. Use the link next to each result.
Questions
Good to know
What is reverse DNS?
Normal DNS turns a name into an address. Reverse DNS turns an address back into a name, using a PTR record held by whoever controls the address block, usually the ISP.
Why does my address have no PTR record?
PTR records are set by the holder of the address block. If you are an ISP's customer, ask your ISP to set one. If you hold the block, add it in your reverse zone.
Who answers these lookups?
Cloudflare's public DNS service (1.1.1.1). Your browser asks it directly; nothing goes through Helpnyx.
More free tools
Other tools you may need
IP lookup
Who holds an IP address: owner, ASN, country, abuse contact.
Open the toolDNS lookup
A, AAAA, MX, NS, TXT and other records for a domain.
Open the toolFCrDNS check
Check that an IP's reverse name points back to it.
Open the toolMAC vendor lookup
Find the maker of a network device from its MAC address.
Open the toolIPv4 subnet calculator
Network, broadcast, usable range and masks for any block.
Open the toolIPv6 subnet calculator
First and last address, size, /64 count and reverse zone.
Open the tool
Still tracking IPs in a spreadsheet?
IPAM Enterprise keeps every /24, block, customer and circuit in one portal, and checks each assignment for overlaps before it is saved.