What is WHOIS and RDAP?

WHOIS (RFC 3912) and its modern JSON replacement RDAP (RFC 7480) query domain registries (Verisign, Nominet, PIR) to return registrar ownership information, registration dates, expiration timelines, and authoritative nameservers.

What is Reverse DNS (rDNS)?

Reverse DNS resolves an IP address into its associated hostname using pointer (PTR) records stored in the in-addr.arpa domain tree. It is essential for anti-spam mail server authentication.

Why is personal contact information redacted in WHOIS results?

Under privacy regulations like GDPR and ICANN's Temporary Specification, registrars redact personal registrant names, emails, and phone numbers to prevent identity theft and spam harvesting.

Network Utility

Domain Tools Hub

WHOIS lookup, domain-to-IP resolver, reverse DNS, and domain availability checker — fast, private, and free.

More Free Network Tools

IPLocatorTools provides a complete suite of fast, open-source network diagnostic utilities with zero installation.

IP Lookup

Find your public IP address, city, ISP and location

DNS Lookup

Query A, MX, TXT, NS and other DNS records

Port Checker

Test open ports with parallel TCP probes

Subnet Math

Calculate CIDR, usable IPs, and binary octets

SSL Checker

Verify SSL certificate validity and expiry date

IP Blacklist

Check if an IP is listed on spam blacklists

Domain Tools — Frequently Asked Questions

Use the WHOIS Lookup tool at IPLocatorTools Domain Tools. Enter the domain name and click Lookup. The registrar name, registration date, expiry date, and nameservers will be shown. Note that many registrants use WHOIS privacy protection which hides personal contact details.

A WHOIS lookup queries the public database of domain registrations. It shows who registered a domain, which registrar they used, when the domain was registered, when it expires, and which nameservers it uses. WHOIS data is mandated to be publicly available by ICANN for most domain extensions.

Reverse DNS lookup finds the hostname associated with an IP address by querying the PTR record in DNS. For example, the reverse DNS of 1.1.1.1 is one.one.one.one. It is commonly used to verify mail server identity and for network troubleshooting.

Use the Domain Availability tool at IPLocatorTools Domain Tools. Select Domain Availability, enter the domain you want, and click Lookup. The tool checks DNS records and RDAP registration data to determine if the domain is registered or likely available.

RDAP (Registration Data Access Protocol) is the modern replacement for WHOIS. It returns structured JSON data instead of plain text, supports internationalized domain names, and provides more consistent responses across registrars. RDAP is now the ICANN-preferred standard for domain registration lookups.

Domain Registration Telemetry: From Legacy WHOIS to Modern RDAP (RFC 7480)

Managing internet domains requires reliable visibility into registration lifecycle events. Historically, the WHOIS protocol (RFC 3912) operated on TCP port 43, returning unstructured plain text without standardized schemas.

The modern internet standard is the Registration Data Access Protocol (RDAP, RFC 7480–7484). RDAP delivers machine-readable JSON over secure HTTPS with built-in internationalization, authenticated access tiers, and granular data privacy controls mandated by ICANN.

Domain Investigation Capabilities & Protocols

Review the four diagnostic modes available in our domain intelligence suite:

Investigation Mode	Input Format	Extracted Telemetry	Primary Use Case
WHOIS / RDAP Lookup	Domain name	Registrar, Created/Expiry dates, Nameservers, Status codes	Ownership verification, expiring domain tracking
Reverse DNS (rDNS)	IPv4 / IPv6 address	PTR records pointing to authoritative hostnames	Mail server validation, IP attribution
Domain to IP Resolver	Domain name	Direct A / AAAA addresses, hosting provider ASN	Server discovery, infrastructure mapping
Domain Availability	Proposed domain	Real-time registry registration status (Available / Registered)	Brand registration, new project domain search

Related Domain & Network Tools