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Reverse DNS (PTR) Generator

PTR: 1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa

About This Tool

The Reverse DNS (PTR) Generator creates the proper reverse DNS lookup domain names for both IPv4 and IPv6 addresses. PTR records are essential for reverse DNS lookups, which convert IP addresses back to domain names. This tool automatically generates the correct in-addr.arpa format for IPv4 addresses and ip6.arpa format for IPv6 addresses, following DNS standards (RFC 1035 for IPv4 and RFC 3596 for IPv6). This is crucial for email server configuration, network troubleshooting, and DNS zone file management.

How to Use

  1. Enter any valid IPv4 address (e.g., 8.8.4.4) or IPv6 address (e.g., 2001:db8::1)
  2. The tool automatically detects the IP version and generates the appropriate PTR record name
  3. Copy the generated PTR name for use in your DNS zone files or reverse DNS configuration
  4. The result is ready to use directly in BIND, PowerDNS, or other DNS server configurations

Features

  • Supports both IPv4 and IPv6 addresses
  • Automatically detects IP address version
  • Generates RFC-compliant PTR record names
  • Real-time generation as you type
  • Produces in-addr.arpa format for IPv4
  • Produces ip6.arpa format for IPv6
  • Output ready for immediate use in DNS zone files

Common Use Cases

  • Configuring reverse DNS zones for mail servers to pass SPF checks
  • Setting up PTR records for email deliverability
  • Creating reverse DNS zone files for network blocks
  • Troubleshooting email delivery issues caused by missing PTR records
  • Configuring DNS for hosting providers and ISPs
  • Setting up reverse DNS for server IP addresses
  • Automating DNS zone file generation
  • Verifying correct reverse DNS configuration before deployment

Technical Details

Reverse DNS (rDNS) uses PTR (pointer) records to map IP addresses back to domain names. The DNS query format is created by reversing the IP address components and appending a special domain.

IPv4 PTR Format (in-addr.arpa):

IPv4 addresses are reversed octet by octet and appended with .in-addr.arpa:

  • IP: 8.8.4.4 → PTR: 4.4.8.8.in-addr.arpa
  • IP: 192.0.2.1 → PTR: 1.2.0.192.in-addr.arpa
  • IP: 10.20.30.40 → PTR: 40.30.20.10.in-addr.arpa

IPv6 PTR Format (ip6.arpa):

IPv6 addresses are expanded to full form, reversed nibble by nibble (half-byte), with dots between each nibble, and appended with .ip6.arpa:

  • IP: 2001:db8::1 → Expanded: 2001:0db8:0000:0000:0000:0000:0000:0001
  • PTR: 1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa

Common Uses:

  • Email servers: Many mail servers reject emails from IPs without proper PTR records
  • Logging: Server logs often show hostnames via reverse DNS lookups
  • Security: PTR records help verify the legitimacy of connecting hosts

This tool ensures correct formatting of PTR record names according to DNS RFCs, preventing common configuration errors.