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Reverse DNS

Available

Look up the PTR record of an IPv4 or IPv6 address to find the hostname it maps to.

Reverse DNS

Public IPv4 or IPv6 address

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How it works

The address is converted to its in-addr.arpa (IPv4) or ip6.arpa (IPv6) name and its PTR record is queried.

Frequently asked questions

Why does an IP have no reverse DNS?

PTR records are set by whoever controls the IP block, usually the ISP or hosting provider. Many addresses simply have none.

Why does reverse DNS matter for email?

Many mail servers reject or flag mail from IPs without a valid PTR record that matches the sending hostname.