title: “WHOIS: How the IP Block Registration and Management System Works”
The internet, as we know it, is unimaginable without IP addresses — unique numerical identifiers that enable devices to communicate with each other. One of the tools that helps track the ownership and management of IP addresses is the WHOIS system.
When internet service providers (ISPs) or data centers acquire an IP block, they are required to register that block in international registries so others can track who owns the range. WHOIS facilitates this process.
How Does WHOIS Work for IP Blocks?
WHOIS is a system that provides access to information about the owners of IP addresses and IP blocks. When an organization acquires an IP block from one of the regional internet registries (RIRs), such as RIPE NCC for Europe or ARIN for North America, they must register this block in the WHOIS database. Using a WHOIS query, anyone can find out who owns a specific IP address or range of addresses, as well as other related information, including:
- The owner of the IP block (company or provider)
- Technical contacts and their details
- The country or region where the IP range is used
- The allocation dates of the IP block
- The subnet to which these addresses belong
How to Use WHOIS to Check IP Blocks?
WHOIS queries for IP addresses or blocks work similarly to domain name queries. You enter an IP address or range (e.g., 192.168.0.0/24), and the system returns all registered information regarding that range. An example query might look like this:
- You enter the IP address (e.g.,
203.0.113.0) into the WHOIS query form. - In response, you receive details about the owner of that IP address, including the organization that owns the address and the contact information of its representatives.
- Information about the registration date and the duration of the IP range will also be displayed.
This data is useful for technical administration and for various legal and business purposes, such as:
- Identifying suspicious traffic sources or malicious actors attacking the network
- Verifying and confirming IP block ownership when leasing IP addresses
- Resolving disputes between providers over IP address ownership
WHOIS and Internet Security
WHOIS is frequently used to address cybersecurity issues. For example, when investigating incidents related to phishing, spam, or DDoS attacks, information about the owner of an IP address or domain obtained via WHOIS can help identify the malicious actors or their infrastructure. Network administrators and security services often use WHOIS to trace sources of malicious traffic and take action to block or file complaints against them.
WHOIS and Domain Disputes
WHOIS plays a key role in resolving domain disputes, especially in cases of cybersquatting — the practice of registering domains similar to well-known brands for resale or fraudulent use. Information from WHOIS allows rightful owners to find out who registered a domain and initiate legal processes to recover it.
WHOIS in the Fight Against Cybercrime
WHOIS is frequently used by law enforcement agencies and organizations to combat cybercrime. If malware is being distributed or fraud is being conducted through an IP address or domain, WHOIS can provide the necessary information for further investigation. This data can assist in identifying the owners of resources and supporting international efforts in fighting cybercrime.
Changes in WHOIS Data Availability
GDPR (General Data Protection Regulation) is a data protection law adopted by the European Union, which came into effect on May 25, 2018. This regulation was designed to give EU citizens and residents greater control over their personal data and establish uniform rules for all organizations processing EU citizens’ data, regardless of their location. After the introduction of GDPR in 2018, many registrars began to hide personal information about domain and IP address owners, reducing the availability of WHOIS data. Now, queries often return only general information, such as registrar details and minimal technical data. This complicates the work of cybersecurity specialists investigating incidents and complicates legal procedures related to domain name or IP address violations.
Conclusion
WHOIS remains an essential tool for managing and administering IP blocks. It allows users to find out who owns IP address ranges and contact the owners if necessary. Despite changes in the availability of personal data, WHOIS continues to play a key role in maintaining transparency and security on the internet.