What is Reverse IP Lookup

A reverse IP lookup is performed to find all records which have an IP address assigned to it. By performing a reverse IP lookup, one can identify the hosts who are being served with the help of a web server.

Reverse IP Lookup
Reverse IP Lookup | Image by ItNeverEnds from Pixabay

Through reverse IP lookup, information can be collected to figure out the vulnerabilities on servers and expand the attack surface. One can use this technique by identifying the hostnames that have a DNS record and an IP address associated with it. In this article, we are going to discuss the concept of such a tool and how it is utilized for various purposes.

The concept of Reverse IP lookup

The tool technique is executed by identifying the hosts who have a DNS record and an IP address assigned to them. It is used to figure out the virtual hosts on a server.

A web server can configure to serve a wide number of virtual hosts from a single IP address. This configuration is standard in multiple network hosting arrangements and organizations which utilize a shared hosting environment. Reverse IP lookup is an efficient technique to expand the attacking surface when pursuing a web server. To state an example of how efficient it is, one can utilize a lookup tool to gain access to the underlying operating software even if the target web page is secured. It is done by attacking a lesser secured web page that is operating on the same server. It bypasses the security barriers of the target site.

A CIDR search can also be performed in addition to reverse IP lookup to look for web hosts using a single IP address. One can search up to 24 hosts on a single IP address using this technique if they are using a free-end software. However, paid software might enable you to go after no less than 500,000 sites from a single query using an API key.

Reverse IP Search using search engines

Bing might appear to be unusable for multiple reasons as a search engine. On the other hand, it is an indispensable tool when it comes to reverse IP lookup. Bing is the only search engine that offers a search query that can resolve the names of the hosts. It can be done using a single IP address. It used to be one of the most popular methods to figure out the virtual web hosts using a single IP address. Bing uses its search index for the lookup IPs. Stating a query shows a list of hosts that matches the query IP address.

The uses of Reverse IP lookup

Following given are the real-world utilities for the tool and how it is used in practical applications:

1) Discovery of vulnerabilities for computer red and blue teams:

During an attack on the host. The first thing that a user attempt is to identify the vulnerabilities of the host. Reverse IP lookup enables the user to figure out the vulnerabilities and the attack areas of the host. After understanding the vulnerabilities, the user enumerates the applications which are being used by the host. It creates an opportunity for the user to exploit the user.

Utilizing this reverse IP technique, one can identify web sites on the host which has the maximum attacking surface and exploitation opportunity. Even if the website appears to be iron-clad, information can be obtained. This information can be used to figure out any minor vulnerability that can be utilized to breach the target.

By merely identifying hostnames related to the target site, one can gain necessary information on the new hostnames which might have an additional DNS record. It can be utilized to acquire new targets.

2) Responding to incidents and gathering information on threats:

Whether providing a response to any incidents on a web server. By identifying any underlying bots which are eating into the traffic of the webserver or gaining information on potentially threatening. A host reverse lookup of the IP can be used to identify the above problems. It can be used to identify the hostnames whose purpose is to attack the webserver. It is a necessary information tool that can be used to nullify threats.

3) Controlling oversubscription and filtering out the non-useful traffic:

If a web server operates on a purchase-based shared environment. The web server might face an overload if it continues to sell small resources to minor websites. Minor websites that use very little data traffic. To increase the efficiency of the web server, a reverse tool for that can be performed to identify how many web sites a particular server can handle. It helps to set up a ceiling limit to a web server. Also, it is recommended to controls the number of hosts on a single web server. It is necessary to keep the efficiency of the webserver intact.

4) Maintaining the reputation of web servers:

Reverse IP lookup can also be utilized to filter out sites of poor quality, spam, blackmail, and phishing based hosts. This information can be obtain from the webserver. It keeps the reputation of the web host intact and allows a zero-tolerance shared-host web environment.

How is the DNS data queried?

The maximum amount of data that is used in the reverse IP lookup tool comes from a web crawl mechanism sourced. This can be from sources like Alexa top 1 million websites, Bing Search, Certificate Transparency list, scans.io project or Common web crawl technique. The query searches through plain text-based host records to find hosts with the matching IP address.

Difference between Reverse DNS Lookup and Reverse IP Lookup

Reverse IP Lookup and Reverse DNS Lookup are a bit different from each other. In IP lookup, it uses text-based records to find hosts with similar IP addresses. However, for reverse DNS lookup, the IP address is checked with the DNS to find out whether there is a PTR record.


Reverse IP Lookup has many utilities in the working world. It is an essential tool that not only exposes the vulnerabilities of a host. It can also serves as a control tool for web servers as well. I hope you liked this article on the concept of it and how to utilize it.

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