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Four Oh Four: A Look at Our Favorite Status Code

Happy 404 day from Censys! Here are some fun stats involving our favorite “resource not found” HTTP status code!

We’ve all experienced it: you’re leisurely browsing the web, surfing along, and suddenly come across this: 404 Page Not Found. When a user encounters a 404 error, it could mean that the user incorrectly entered the URL or the page has been deleted or moved.

While 404 error messages can be annoying, they actually serve an essential function in keeping the web user-friendly. They help website owners identify broken and dead links lurking around, keeping those links from cluttering search engine results.

Four-Oh-Fours are less widespread than one may think on the default internet: only 7.7% of HTTP services return a 404 status code when requesting the base path, meaning 92% of the web is not lost! So that’s a good thing.

There are a lot of different 404 status messages out there, but the most common is the good old case-sensitive “Not Found” with almost 170 million servers.

While we’re at it, why not look at the different types of services that listen on port 404 in our internet data?

Searching for services running on port 404 yielded slim results, and the ones we found were shrouded in mystery. So one could say the service name is 404 too.


Use this Censys Search Query to investigate port 404 yourself – and don’t forget to tweet @censysio if you discover anything interesting.

Any celebration of 404 day here at Censys is incomplete without a 404 joke, so here we go:

“Why did the web developer feel lost? Because they kept finding Not Found pages everywhere they went!”

(This joke was AI-generated and returned the following error: 404 humor not found)

About the Author

Himaja Motheram
Security Researcher
Himaja Motheram is a Security Researcher at Censys, working on answering interesting questions about the Internet using Censys Search data.
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