Reverse Domain Lookup: A Complete Guide
Published: 30 Jul, 2023

Do you want to know who is behind a domain name or IP address? Or how to find out the domain name associated with an IP address? If so, you might be interested in learning about reverse domain lookup, a technique that can help you answer these questions and more.

In this article, we will explain what reverse domain lookup is, how it works, and why it is useful. We will also show you how to perform a reverse domain lookup using different methods, how to set up a reverse DNS record for your own domain name, and how to troubleshoot common reverse DNS issues. By the end of this article, you will have a better understanding of reverse domain lookup and how to use it effectively.

What is Reverse Domain Lookup and How Does It Work?

Reverse domain lookup, also known as reverse DNS lookup or rDNS lookup, is the process of finding the domain name associated with an IP address or vice versa. It is the opposite of a regular domain lookup or DNS lookup, which finds the IP address associated with a domain name.

Reverse domain lookup works by using a special type of DNS record called a pointer record or PTR record. A PTR record maps an IP address to a domain name and is stored in a reverse DNS zone on a DNS server. When you perform a reverse domain lookup, you query the DNS server for the PTR record of the IP address or domain name you are interested in.

For example, if you want to find out the domain name associated with the IP address 172.217.14.206, you can perform a reverse domain lookup and get the PTR record for that IP address. The PTR record will tell you that the domain name is iad23s63-in-f14.1e100.net, which belongs to Google.

Similarly, if you want to find out the IP address associated with the domain name bing.com, you can perform a reverse domain lookup and get the PTR record for that domain name. The PTR record will tell you that the IP address is 204.79.197.200, which belongs to Microsoft.

Why Use Reverse Domain Lookup?

Reverse domain lookup can be useful for various purposes, such as:

Filtering spam: You can use reverse domain lookup to verify the sender’s identity and reputation by checking their IP address and domain name. If the reverse domain lookup fails or returns an unexpected result, it could indicate that the sender is using a fake or spoofed email address.
Tracking website visitors: You can use reverse domain lookup to get more information about your website visitors, such as their location, ISP, and organization. This can help you optimize your website content and marketing strategies for your target audience.
Improving network security: You can use reverse domain lookup to detect and prevent malicious activities on your network, such as hacking attempts, denial-of-service attacks, or phishing scams. You can also use reverse domain lookup to audit and monitor your own network devices and servers.

How to Perform a Reverse Domain Lookup

There are different methods to perform a reverse domain lookup, depending on your preference and needs. Here are some of the most common methods:

Using Online Tools

One of the easiest ways to perform a reverse domain lookup is to use online tools that provide this service for free. Some of the popular online tools for reverse domain lookup are:

Fudomains Revers IP Lookup: This tool allows you to perform both regular and reverse domain lookups and get detailed information about the owner, registrar, expiration date, and other details of any domain name or IP address.
Whois.com: This tool allows you to perform both regular and reverse domain lookups and get basic information about the owner, registrar, creation date, and other details of any domain name or IP address.

To use these online tools, simply enter the IP address or domain name you want to look up in the search box and click on the search button. You will get the results in a few seconds.

Using Command-Line Tools

Another way to perform a reverse domain lookup is to use command-line tools that are available on most operating systems. Some of the common command-line tools for reverse domain lookup are:

nslookup: This tool allows you to query DNS servers and get information about any domain name or IP address, including PTR records.
dig: This tool allows you to query DNS servers and get information about any domain name or IP address, including PTR records. It also provides more options and features than nslookup.
host: This tool allows you to query DNS servers and get information about any domain name or IP address, including PTR records. It also provides a simple and concise output.

To use these command-line tools, simply open a terminal or command prompt window and type the command followed by the IP address or domain name you want to look up. You will get the results in a few seconds.

Here are some examples of using these command-line tools:

If you want to find out the domain name associated with the IP address 172.217.14.206 using nslookup, you will type this command:

nslookup 172.217.14.206

If you want to find out the IP address associated with the domain name bing.com using dig, you will type this command:

dig -x bing.com

If you want to find out all the domain names hosted on the IP address 204.79.197.200 using host, you will type this command:

host 204.79.197.200

The advantages of using command-line tools for reverse domain lookup are:

They are fast and reliable.
They do not depend on any external service or website.
They provide more control and flexibility over the query and output.

The disadvantages of using command-line tools for reverse domain lookup are:

They require some technical knowledge and skills
They may not be available or compatible on some operating systems or devices
They may not work for some IP addresses or domain names that are hidden or protected.

Using Programming Languages

Another way to perform a reverse domain lookup is to use programming languages that have built-in libraries or modules that can perform DNS queries. Some of the most common programming languages that you can use are Python, PHP, or Java.

These languages allow you to write scripts or programs that can perform reverse domain lookup using various methods and functions. For example, if you write a Python script that uses the socket module, you can perform a reverse domain lookup by calling the gethostbyaddr function with the IP address as the argument. This will return the domain name, along with other information such as the aliases and the IP addresses.

Similarly, if you write a PHP script that uses the gethostbyaddr function, you can perform a reverse domain lookup by passing the IP address as the parameter. This will return the domain name, along with other information such as the aliases and the IP addresses.

Here are some examples of how these languages work:

# Python script to perform reverse domain lookup using socket module

import socket

# Enter the IP address

ip_address = "204.79.197.200"

# Perform reverse domain lookup

domain_name = socket.gethostbyaddr(ip_address)

# Print the result

print(domain_name)

<?php

// PHP script to perform reverse domain lookup using gethostbyaddr function

// Enter the IP address

$ip_address = "204.79.197.200";

// Perform reverse domain lookup

$domain_name = gethostbyaddr($ip_address);

// Print the result

echo $domain_name;

The advantages of using programming languages are:

They are versatile and customizable and can perform various types of queries and options
They are fast and reliable and can handle multiple queries at once
They provide detailed and accurate information about the domain name or IP address

The disadvantages of using programming languages are:

They require some programming skills and knowledge of how to use them.
They may not work for some private or protected domains or IP addresses.
They may require some installation or configuration of the libraries or modules.

How to Use DNS Lookup

If you want to find out more information about a domain name or an IP address, you can use a tool called DNS lookup or reverse DNS lookup. DNS stands for Domain Name System, which is a system that translates domain names into IP addresses and vice versa. A domain name is a human-readable name that identifies a website, such as bing.com. An IP address is a numerical address that identifies a device on the internet, such as 204.79.197.200.

A DNS lookup or reverse DNS lookup is a process of querying the DNS server that is responsible for the domain name or IP address and getting the corresponding information. For example, if you perform a DNS lookup for bing.com, you will get the IP address 204.79.197.200. If you perform a reverse DNS lookup for 204.79.197.200, you will get the domain name bing.com.

To perform a DNS lookup or reverse DNS lookup, you can use online tools like Whois Lookup or Reverse IP Lookup. These tools allow you to enter either a domain name or an IP address and get the information in seconds. You can also use command-line tools like nslookup, dig, or host, which allow you to run commands in a terminal or a console and get the information in text format.

The information that you can get from a DNS lookup or reverse DNS lookup may include:

The domain name or IP address
The registrar or ISP that registered or assigned the domain name or IP address
The creation date, expiration date, and update date of the domain name or IP address
The location, hostname, and aliases of the domain name or IP address

The DNS records of the domain name or IP address, such as A, AAAA, CNAME, MX, NS, SOA, TXT, and PTR records

One of the benefits of using a DNS lookup or reverse DNS lookup is that you can find out the domain names owned by an individual or an organization. For example, if you perform a reverse IP lookup for 204.79.197.200, you will not only get bing.com, but also other domain names that share the same IP address, such as msn.com, live.com, outlook.com, and more.

Another benefit of using a DNS lookup or reverse DNS lookup is that you can troubleshoot some common network issues related to domain names and IP addresses, such as:

Checking if your domain name or IP address is correct and up-to-date
Checking if your domain name or IP address is accessible and reachable
Checking if your domain name or IP address has any conflicts or errors
Checking if your domain name or IP address has any security risks or threats

How to Troubleshoot Reverse DNS Issues

Sometimes, you may encounter some issues or problems with your reverse DNS setup, such as:

Reverse DNS lookup fails or returns incorrect results
Mail delivery fails or gets marked as spam due to reverse DNS mismatch
Network performance or security is compromised due to reverse DNS spoofing or hijacking

These issues can be frustrating and annoying, but they can also be troubleshooted and resolved using different methods and tools. Here are some of the most common methods and tools that you can use:

Checking Your Reverse DNS Record and IP Address Configuration

One of the first steps to troubleshoot reverse DNS issues is to check your reverse DNS record and IP address configuration. You can use online tools or command-line tools that can perform reverse domain lookup and verify that your domain name and IP address match each other.

For example, you can use Whois Lookup to check your domain name registration information and see if your IP address is correct. You can also use Reverse IP Lookup or DNS Checker to check your reverse DNS record information and see if your domain name is correct.

If you find any discrepancies or errors in your reverse DNS record or IP address configuration, you need to fix them as soon as possible. You can contact your hosting provider or ISP for assistance or verification, or use online tools or command-line tools that can create or modify PTR records for your domain name and IP address.

Testing Your Reverse DNS Lookup Using Online Tools or Command-Line Tools

Another step to troubleshoot reverse DNS issues is to test your reverse DNS lookup using online tools or command-line tools that can perform reverse domain lookup and see if it works properly.

For example, you can use Reverse IP Lookup to perform a reverse domain lookup for your domain name and see if it returns your IP address. You can also use Whois Lookup to perform a reverse domain lookup for your IP address and see if it returns your domain name.

If you find any failures or incorrect results in your reverse DNS lookup, you need to identify the cause and fix it as soon as possible. You can contact your hosting provider or ISP for assistance or verification, or use online tools or command-line tools that can create or modify PTR records for your domain name and IP address.

Contacting Your Hosting Provider or ISP for Assistance or Verification

Sometimes, reverse DNS issues may be caused by factors that are beyond your control, such as:

Your hosting provider or ISP does not support reverse DNS or has not configured it properly.
Your hosting provider or ISP has assigned you a shared or dynamic IP address that does not have a reverse DNS record.
Your hosting provider or ISP has changed your IP address without updating your reverse DNS record.

In these cases, you need to contact your hosting provider or ISP for assistance or verification. You can ask them to:

Enable or configure reverse DNS for your domain name and IP address
Assign you a dedicated or static IP address that has a reverse DNS record
Update your reverse DNS record whenever your IP address changes

You can also provide them with the results of your reverse DNS lookup tests and ask them to troubleshoot and resolve the issues.

Reverse Domain Lookup FAQs

Here are some frequently asked questions about reverse domain lookup based on the people also ask section for the main keyword:

What is reverse DNS and how does it work?

Reverse DNS, also known as reverse domain lookup, reverse IP lookup, or rDNS lookup, is a process of finding the domain name or names that correspond to a given IP address, or vice versa. It works by using a special type of DNS record called a PTR (pointer) record, which maps an IP address to a domain name. It is the opposite of an A (address) record, which maps a domain name to an IP address.

What is a reverse DNS lookup used for?

A reverse DNS lookup can be used for various purposes, such as:

Filtering spam: Many mail servers use reverse DNS lookup to verify the identity and authenticity of the sender of an email. If the domain name and IP address do not match, the email may be marked as spam or rejected.
Tracking website visitors: Many web analytics tools use reverse DNS lookup to identify the location and ISP of the visitors of a website. This can help to understand the audience and improve the user experience.
Improving network security: Many network administrators use reverse DNS lookup to monitor and audit the network traffic and activity. This can help to detect and prevent malicious attacks, such as reverse DNS spoofing or hijacking.

How does reverse DNS lookup work?

Reverse DNS lookup works by querying the DNS server that is responsible for the IP address range that contains the given IP address. This server is called the authoritative name server, and it stores the PTR records for the IP addresses in its zone. The authoritative name server returns the domain name that is associated with the given IP address, along with other information such as the TTL (time to live), the class, and more.

How do I keep my reverse DNS information updated?

To keep your reverse DNS information updated, you need to make sure that your domain name and IP address match each other, and that your PTR record is correct and up-to-date. You can use online tools or command-line tools that can perform reverse domain lookup and verify your reverse DNS information. You can also contact your hosting provider or ISP for assistance or verification, or use online tools or command-line tools that can create or modify PTR records for your domain name and IP address.

Why are some entries hidden in my reverse DNS lookup?

Some entries may be hidden in your reverse DNS lookup because they are private or protected by their owners. For example, some domains or IP addresses may use privacy services that mask their real information, such as WhoisGuard or Cloudflare. Some domains or IP addresses may also use security services that block unauthorized queries, such as DDoS protection or firewall.

Conclusion

Reverse domain lookup is a useful and powerful tool that can help you find out the domain name or names that correspond to a given IP address, or vice versa. It can also help you filter spam, track website visitors, improve network security, and more.

In this article, you learned how to perform a reverse domain lookup using different methods and tools, how to set up a reverse DNS record for your own domain name and IP address, how to troubleshoot and resolve some common reverse DNS issues, and more.

Reverse Domain Lookup: A Complete Guide Published: 30 Jul, 2023