---
title: whois — Domain and IP registration lookup
date: 2026-10-20
time: 12:00
model: admin
category: programs
author_type: human
summary: Looks up registrar, registrant, name servers and contacts for a domain or address block.
tags: program, Network and Firewall, whois
---

Looks up registrar, registrant, name servers and contacts for a domain or address block.

## Basic Information

| Command Name | whois |
| --- | --- |
| One-line Introduction | Looks up registrar, registrant, name servers and contacts for a domain or address block. |
| Provided by | whois client (packaged by distributions) |
| Official Documentation | https://man7.org/linux/man-pages/man1/whois.1.html |
| Supported Operating Systems | Linux, macOS, BSD |
| Installation Status | Package required (apt install whois) |
| Category | Linux networking (tags: Address, port and firewall management (tags: domain, registration, IP, lookup)) |

## What is this command?

whois fetches registration data for domains and address blocks from registry servers.

It shows registrar, name servers, expiry dates and contacts, useful for domain administration.

## What problems does it solve?

- Check the registrar and expiry date of a domain.
- See which name servers the domain is delegated to.
- Find the allocation owner of an address block.
- Trace the network owner behind suspicious traffic.
## Key features

### Domain lookup

Passing a domain name fetches its registration data.

- **When to use**: When checking ownership or expiry.
- **What you get**: Registrar, status, name servers and expiry are printed.
- **Limitations**: Privacy policies may redact some fields.
### Address block lookup

Passing an IP address looks up the block that contains it.

- **When to use**: When identifying who operates a source network.
- **What you get**: The allocating registry and network name appear.
- **Limitations**: Contact details differ between registries.
### Choose a server

You can query a specific whois server.

- **When to use**: When querying a national registry directly.
- **What you get**: The raw answer of that server is shown.
- **Limitations**: Query formats and limits vary by server.
## Installation and usage

### Check whether it is installed

```
whois -h whois.example.net example.com
```

sudo apt install whois

## Real-world examples

### Domain data

Fetch domain registration data.

```
whois example.com
```

### Address block

Inspect the block that owns an address.

```
whois 203.0.113.10
```

### Trim output

Keep only the fields of interest.

```
whois example.com | grep -Ei 'registrar|expiry|name server'
```

---
Source (HTML): https://games.aidebatehub.com/programs/linux/network/whois.html
This file is an auto-generated Markdown twin of the DevHub document.