Reverse DNS Lookup
Check the PTR hostname for a public IPv4 or IPv6 address from multiple global Agent locations.
Run a global PTR lookup
Live worldwide results
Reverse DNS results
| Location | Status | Resolver | PTR hostnames |
|---|
What reverse DNS shows
Reverse DNS looks for PTR records under the reverse namespace associated with an IP address. Each NetOpsKit Agent performs the same lookup so you can compare resolver answers and caching behavior across locations.
Understanding the result
A PTR value is a hostname published by the IP range operator. It can describe a mail server, hosting node, router, or other infrastructure, but it does not prove ownership of the service using the address.
Forward-confirmed reverse DNS
Some systems additionally check whether the PTR hostname resolves forward to the original IP. This page reports the PTR answer itself; use DNS Lookup to inspect the hostname's A and AAAA records.
Common issues
An empty NOERROR answer usually means that no PTR has been configured. NXDOMAIN means the reverse name does not exist. Different cached TTL states can briefly produce regional differences after a change.
Frequently asked questions
What is a PTR record?
A PTR record maps an IP address back to a hostname. It is stored under the special in-addr.arpa namespace for IPv4 or ip6.arpa namespace for IPv6.
Is reverse DNS the opposite of an A record?
Conceptually yes, but the records are managed independently. A forward record can point to an IP even when that IP has no PTR record, and the PTR hostname does not have to point back unless the operator configures it that way.
Why is reverse DNS important for email?
Mail systems commonly check whether a sending server has a sensible PTR record and whether its forward DNS agrees. A PTR record alone does not guarantee email reputation or delivery.
Why do some IP addresses have no PTR result?
Only the organization controlling the IP range can delegate or publish reverse DNS. Many public client, CDN, and temporary cloud addresses intentionally have no PTR record.
Can this tool query private IP addresses?
No. Private, loopback, link-local, reserved, and other special-purpose addresses are rejected before tasks are sent and checked again by every Agent.