Question

Use the whois utility/service to find out who is in charge of your site, at least as far as the InterNIC is concerned. Look up your site both by DNS name and by IP network number; for the latter you may have to try an alternative whois server (e.g., whois -h whois.arin.net...). Try princeton.edu and cisco.com as well.

Short answer

Use `whois princeton.edu` and `whois cisco.com` for domain lookups. Use `nslookup` to get IP addresses, then use `whois IP_ADDRESS` for IP lookups, and `whois -h whois.arin.net IP_ADDRESS` if necessary.

Step-by-step solution

- Access Command Line Interface (CLI)

Open a terminal window or command prompt on your computer where you can run command-line utilities.

- Perform Whois Lookup by DNS Name

To find information about the domain princeton.edu, enter the following command: typing `whois princeton.edu` and pressing Enter. This will provide details about the domain owner, administrative contacts, and more.

- Perform Whois Lookup by IP Address

First, find the IP address of the domain using the `nslookup` utility. For example, typing `nslookup princeton.edu` will return the IP address associated with the domain. Next, perform a whois lookup using the obtained IP address: typing `whois IP_ADDRESS` (replace IP_ADDRESS with the actual IP) in the terminal and pressing Enter.

- Alternative Whois Server

If the standard whois lookup does not provide the necessary information for an IP address, use an alternative whois server. For instance, you can type `whois -h whois.arin.net IP_ADDRESS` and press Enter.

- Repeat for Cisco.com

Repeat Steps 2 to 4 for the domain cisco.com. Use `whois cisco.com` for the domain lookup and `nslookup cisco.com` followed by `whois IP_ADDRESS` for the IP address lookup.

Key concepts

Domain Information Lookup

The whois utility is a powerful tool to retrieve information about domain name registrations. It provides details such as the domain owner's name, contact information, and important dates like registration and expiration. When you run `whois princeton.edu`, you'll get a comprehensive report, which typically includes:

• Registrant information
• Administrative contacts
• Technical contacts
• Domain registration dates

By examining this data, you can understand who manages the domain and get insights into its registration history.

IP Address Lookup

IP address lookup is essential for identifying the network location of a domain. This can be achieved through tools like `nslookup`, which translates a domain name into its associated IP address. For example, running `nslookup princeton.edu` will provide the IP address of the server hosting the domain.
Once you have the IP address, you can use the whois utility to fetch detailed information about the IP. For instance, running `whois IP_ADDRESS` (replace IP_ADDRESS with the actual value) will give you details about:

• IP range ownership
• Network provider
• Geographical location

Understanding these details can help you assess the infrastructure and geographic distribution of servers.

nslookup Utility

The `nslookup` utility is a DNS query tool used to discover the IP address corresponding to a domain name. It's essential for troubleshooting internet connectivity issues and verifying addresses.
Example usage:
`nslookup princeton.edu`
This command returns:

• The domain's IP address
• Authoritative name servers

Using `nslookup`, you can verify whether a domain name points to the correct IP and check if DNS records are configured properly.

Alternative Whois Servers

Sometimes, the standard whois server may not provide sufficient information about an IP address. In such cases, using an alternative whois server can be helpful. For example, `whois -h whois.arin.net IP_ADDRESS` will query the ARIN (American Registry for Internet Numbers) database specifically.
Using alternative whois servers ensures you get:

• Expanded data coverage
• Regional-specific information

This can be particularly useful when trying to resolve complex network issues or understand the underlying structure of a network.

Command-Line Interface (CLI)

The Command-Line Interface (CLI) is a text-based interface used to interact with the computer system. It's essential for executing commands directly and receiving immediate feedback.
Steps to access the CLI:

• Open a terminal window (Linux, macOS) or command prompt (Windows)
• Type the desired command
• Press Enter to execute

Using the CLI for tasks like whois and nslookup offers various advantages:

• Faster execution
• Automated scripting capabilities
• Greater control over command parameters

Mastering the CLI can significantly enhance your productivity in managing and troubleshooting networks.