IP-address: | 3.21.21.5 |
Host: | ec2-3-21-21-5.us-east-2.compute.amazonaws.com |
Internet Service Provider (ISP): | AS16509 Amazon.com, Inc. |
Country: | United States of America |
Region: | Ohio |
Place: | Columbus |
Postal code: | 43215 |
Est. location data: | 39.9612,-82.9988 |
Timezone: | America/New_York |
In fact, not only web servers but any online device can be identified with this method, and allowing us to look up some basic information about the IP-address you provided.
The standard of IP-addresses has been IPv4 for quite long, which, in a human readable format, consists of four numbers, each ranges from 0 to 255: e.g. 3.21.21.5. This allows ~4,294,967,296 different IP-addresses to be assigned to different devices (and yes, that's a lot).
However, due to so many devices connecting to the internet, a newer standard has been finalized to allow even more connections - that is IPv6. Learn more about the background here: https://en.wikipedia.org/wiki/IP_address