Turn an IP into its reverse DNS name.

A PTR record generator takes an IPv4 or IPv6 address (or CIDR) and builds the arpa name used for reverse DNS — reversing the address and appending in-addr.arpa for IPv4 or ip6.arpa for IPv6. This tool does that conversion entirely in your browser, so the IP address you enter is never uploaded to any server.

Forward DNS maps a name to an address; reverse DNS does the opposite — it maps an IP address back to a hostname using a PTR record. The lookup is done under the special in-addr.arpa (IPv4) or ip6.arpa (IPv6) domain, where the address is written backwards as a name. This helper builds that PTR name for you from any address or CIDR.

A PTR record maps an IP address back to a hostname — the reverse of an A or AAAA record. It is mainly used to verify mail servers: many receiving mail servers reject messages from IPs that do not have a valid PTR record. PTR records also appear in system logs and network traces, replacing raw IP addresses with readable hostnames for easier troubleshooting.

No. The PTR name and reverse zone are derived 100% client-side in your tab — there is no server, no account and no logging. You can safely paste internal addresses and private ranges.

IPv4 reverses the four decimal octets and appends in-addr.arpa — so 192.0.2.10 becomes 10.2.0.192.in-addr.arpa. IPv6 expands the address to its 32 hex nibbles, reverses them and appends ip6.arpa, giving a much longer name with one label per nibble. The helper handles both and shows the fully expanded IPv6 form.

A nibble is a single hexadecimal digit (4 bits). IPv6 ip6.arpa names list every nibble of the fully expanded address in reversed order, separated by dots — 32 nibbles total for a host record. For example, 2001:db8::1 expands to 2001:0db8:0000:…:0001, and the reversed nibble sequence becomes 1.0.0.0.…0.8.b.d.0.1.0.0.2.ip6.arpa. The generator shows this nibble breakdown so you can verify the PTR name before adding it to your zone file.

The reverse zone is the part of the arpa tree your DNS server is delegated authority over — for a /24 that is the three-octet zone like 2.0.192.in-addr.arpa. IPv4 delegations fall naturally on octet boundaries (/8, /16, /24). For prefixes finer than /24, RFC 2317 classless delegation is used, where the zone label encodes the sub-/24 block; the helper flags this case so you know a CNAME-style delegation is required.

For IPv4, take the network prefix octets and reverse them: a /24 like 198.51.100.0/24 maps to the zone 100.51.198.in-addr.arpa, while a /16 like 198.51.0.0/16 maps to 51.198.in-addr.arpa. IPv6 reverse zones must fall on nibble boundaries (prefix length divisible by 4); if your prefix is not on a boundary the tool rounds down to the enclosing nibble boundary and notes the discrepancy. Enter any CIDR and the reverse zone generator derives the correct zone name automatically.

No. It does not send any query or resolve anything — it generates the in-addr.arpa / ip6.arpa names and the reverse zone offline, purely from the address you type. To actually resolve a PTR you would use a tool like dig -x or host; this helper just builds the correct names to put in your zone file or query.