What Happens When You Visit a Website in an Internet Browser
When you visit a website in your browser, the browser needs to fetch the website’s content from a server. However, it can’t locate the server with just the website name alone. The browser triggers a query to a DNS (Domain Name System) server, which is a special type of database containing records that match domain names (like example.com) to their corresponding IP addresses—the unique addresses of the servers hosting the content.
This process of finding the IP address associated with a domain name is called DNS resolution. During DNS resolution, the domain name (such as example.com) is converted into an IP address that computers use to find each other on the internet.
With the IP address in hand, the browser establishes a connection to the web server at that IP address and retrieves the requested webpage for you to view.
Check out how internet (generally) works from this post: Internet from scratch in 10 slides
How is the IP to Hosted Domains Database Generated?
- IPinfo’s crawler service regularly scans websites across the internet.
- It determines the IP address that each website resolves to, noting whether the site is hosted on a web server, a CDN, or if it redirects to another server.
- IPinfo aggregates this information to map each website to its resolved IP address.
- By analyzing this data from the reverse perspective, IPinfo identifies the collection of websites associated with each IP address, thereby creating a list of domains “hosted” on each IP.
From this process, IPinfo builds the hosted domains database, which powers our hosted domains API service.
Reverse DNS vs. IP-to-Hosted-Domains Database
Reverse DNS (rDNS) does not capture all the domains hosted on an IP address. Instead, rDNS maps an IP address to a single domain name, typically the primary or canonical domain configured for that IP. Reverse DNS looks up PTR (pointer) records for an IP address, returning only one domain name associated with that IP, so it cannot reflect multiple hosted domains.
In contrast, IPinfo’s hosted domains database creates a more comprehensive map of IP-to-domain relationships by actively visiting websites and observing where each website resolves. This approach provides a robust way to gather data on all domains hosted on a given IP, including cases of shared or co-hosting environments, where multiple domains point to the same IP address. This makes the hosted domains database far more informative and practical than reverse DNS alone.
For example, the Reverse DNS (rDNS) points [208.80.154.224](https://ipinfo.io/208.80.154.224) to a single domain, text-lb.eqiad.wikimedia.org. But the IP address hosts about 70 domains.
