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CompTIA Linux+ XK0-005 - 1.5 - Name Resolution: whois

In Linux, name resolution refers to the process of translating domain names into IP addresses or retrieving information about domain names and IP addresses from DNS servers. It plays a crucial role in network communication and enables us to access websites, send emails, and perform various network-related tasks. This guide will explore the whois command, which allows you to retrieve domain name registration information from the WHOIS database. We will discuss its usage, command examples, and the information it provides.

Understanding the whois Command

The whois command is a tool for obtaining detailed information about domain names, IP addresses, and network resources. It queries the WHOIS database, which contains registration information about domain names and their associated entities, such as registrants, administrators, and name servers. By using the whois command, you can retrieve valuable information, including domain ownership, registration dates, contact details, and more.

Retrieving Domain Information

To retrieve information about a specific domain, use the following command:


Example output:

Domain Name: EXAMPLE.COM
Registry Domain ID: 123456789_DOMAIN_COM-VRSN
Registrar WHOIS Server:
Registrar URL:
Updated Date: 2023-01-15T12:34:56Z
Creation Date: 2000-01-01T00:00:00Z
Registrar Registration Expiration Date: 2024-01-01T23:59:59Z
Registrar: Example Registrar, Inc.
Registrar IANA ID: 1234
Registrar Abuse Contact Email:
Registrar Abuse Contact Phone: +1.5555555555
Domain Status: clientTransferProhibited
Registry Registrant ID: ABC12345
Registrant Name: John Doe
Registrant Organization: Example Company
Registrant Street: 123 Example Street
Registrant City: Anytown
Registrant State/Province: State
Registrant Postal Code: 12345
Registrant Country: US
Registrant Phone: +1.5555555555
Registrant Email:
Registry Admin ID: DEF67890
Admin Name: Jane Smith
Admin Organization: Example Company
Admin Street: 456 Example Street
Admin City: Anytown
Admin State/Province: State
Admin Postal Code: 12345
Admin Country: US
Admin Phone: +1.5555555555
Admin Email:
Registry Tech ID: GHI98765
Tech Name: Tech Support
Tech Organization: Example Company
Tech Street: 789 Example Street
Tech City: Anytown
Tech State/Province: State
Tech Postal Code: 12345
Tech Country: US
Tech Phone: +1.5555555555
Tech Email:
DNSSEC: unsigned
URL of the ICANN WHOIS Data Problem Reporting System:

The output provides comprehensive information about the domain "", including the registrar, registration dates, registrant information, administrative contacts, technical contacts, and more.

Searching for IP Address Information

You can also use the whois command to retrieve information about a specific IP address. For example:


Example output:

NetRange: -
NetName:        EXAMPLE-NET
NetHandle:      EXAMPLE-NET
Parent:         NET-192-0-2-0-1
NetType:        Example Network
OriginAS:       AS12345
Organization:   Example Organization
RegDate:        2000-01-01
Updated:        2023-05-01


OrgName:        Example Organization
OrgId:          EXAMPLE
Address:        123 Example Street
City:           Anytown
StateProv:      State
PostalCode:     12345
Country:        US
RegDate:        2000-01-01
Updated:        2022-12-31


In this example, we queried the whois command with the IP address "". The output provides information about the IP address range, including the net range, CIDR notation, net name, and related details such as the organization, registration date, and contact information.


The whois command is a valuable tool for retrieving domain name and IP address registration information from the WHOIS database. It allows you to gather essential details about domain ownership, registration dates, contact information, and more. By using the whois command, you can gain insights into the background and registration status of various network resources. Whether you need to investigate a domain name or retrieve information about an IP address, the whois command provides a convenient way to access the WHOIS database and obtain relevant details.

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