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PTR Zone Generator

Generate a BIND-format reverse DNS zone file from a subnet CIDR. Supports standard /8, /16, /24 subnets and classless /25-/31 delegation per RFC 2317.

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PTR Record Lookup

Look up the PTR (reverse DNS) record for any IPv4 address. PTR records map IPs back to hostnames.

DNS Lookup

Query any DNS record type for any domain - A, AAAA, MX, TXT, CNAME, NS, SOA, CAA. Results come from Cloudflare's global DNS resolver (1.1.1.1).

DNS Zone Diff

Compare two DNS zone files. Paste your original and modified zones to see exactly which records changed. Runs entirely in your browser.

About this tool

The PTR Zone Generator creates a complete BIND-format reverse DNS zone file from a subnet CIDR. Reverse DNS maps IP addresses back to hostnames via PTR records. The zone name follows in-addr.arpa convention: for 10.1.2.0/24 the zone is 2.1.10.in-addr.arpa (octets reversed from the network address).

For classless subnets (/25 through /31), the tool uses RFC 2317 classless delegation. The zone name becomes startOctet/prefix.C.B.A.in-addr.arpa to avoid conflicts with the parent /24 zone. This pattern requires the ISP or parent zone to delegate the classless zone via CNAME records.

Enter optional IP,hostname pairs (one per line) to automatically generate PTR records. Bare hostnames without a domain are qualified with your domain suffix. Fully qualified names (containing a dot) are kept as-is with a trailing dot appended. All processing runs in your browser.