rDNS stands for Reverse Domain Name System. In the (standard) Domain Name System (DNS), domains resolve to a server’s IP address. If you visit the website comcastbusiness.net, you will be forwarded to the IP address 165.160.15.20, which is the IP address of the server hosting the website.
Similarly, all these websites point to the IP address 20.76.201.171
msftcorp.com
msftc.com
msft.pt
msft.info
go.microsoft
When you visit the above websites, you will be forwarded to the IP address 20.76.201.171.
Many websites can point to the same IP address. These websites can be hosted on the server’s IP address, or the IP address can be used in a CDN. For example:
3.33.130.190is an AWS IP and hosts 29 million domains34.98.99.30is a GCP IP and hosts 7 million domains185.230.63.107is a Wix IP and hosts 7 million domains
The hosted domains database aggregates all the domains to IP address resolutions. It considers virtually all the domains out there and determines to which IP address each domain resolves. Then, it lists those IP addresses and domains in an array.
The difference between rDNS and hosted domain data is that rDNS points to the name of the IP address and usually does not indicate a domain itself. The IP address 3.33.130.190 has the rDNS domain of awsglobalaccelerator.com. The rDNS entry ranges from 3.33.204.140 to 3.33.204.152. On the other hand, hosted domains just list domains hosted on specific IP addresses.
Hosted domain data also includes multiple entries of domains into multiple IP addresses if they are included in a CDN. For example: vs global.com resolves to 3.33.152.147, 15.197.142.173 and 204.246.191.62, which are all AWS Cloudfront CDN IP addresses.
The hosted domain database also accounts for domain redirections. For example, robremus.com redirects to a LinkedIn profile. However, in our Hosted Domains data, we mention that the site hosted on 13.107.42.14 indicates that it ultimately redirects or resolves to that IP address, which is the LinkedIn IP address.