In computers, what is the three-digit number used in the error messaging system?

When you are trying to find something on the web or can't connect with a website, sometimes you will be transferred to HTTP 404, more commonly known as the error page.

When communicating via HTTP (Hypertext Transfer Protocol), a server is required to respond to a request, such as a web browser request for a web page, with a numeric response code and an optional, mandatory, or disallowed (based upon the status code) message. In the code 404, the first digit indicates a client error, such as a mistyped Uniform Resource Locator (URL). The following two digits indicate the specific error encountered. HTTP's use of three-digit codes is similar to the use of such codes in earlier protocols such as FTP and NNTP.

At the HTTP level, a 404 response code is followed by a human-readable "reason phrase". The HTTP specification suggests the phrase "Not Found"and many web servers by default issue an HTML page that includes both the 404 code and the "Not Found" phrase.

A 404 error is often returned when pages have been moved, deleted or just broken. In the first case, it is better to employ URL mapping or URL redirection by returning a 301 Moved Permanently response, which can be configured in most server configuration files, or through URL rewriting; in the second case, a 410 Gone should be returned. Because these two options require special server configuration, most websites do not make use of them.

In pop culture, 404 has come to mean someone is clueless in the UK.

More Info: en.wikipedia.org

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10 Comments

Tom Bombara

I agree with others, while 404 is a specific http error, it is incorrect to describe a generic error messaging system. If the question had been phrased to describe which of the choices indicated an error locating a web page, that would be more correct. As it is, it should be removed.

Ian Swindale

I did not understand much of the answer but I'm not technically minded

Eugene Blaettler

A very poorly phrased question. I've been in computers since 1973 and had no idea what it was asking for. It asks for the 3-digit code in the messaging system, but gives no indication what the code was in response to. There are hundreds of 3 digit codes and each has a different meaning.

twohowlingdogs

I can add any error code number to my software I write. But figured this was referring to the most common INTERNET error code. "There are only 10 kinds of people who understand binary."

Gery Tillmanns

That was easy, I get it all the time! LOL

situations

fcowell, I thought this question was poorly phrased, as there are hundreds of computer error codes! I went with 404 because it is commonly seen when searching on the internet. There is a computer error code 303 which indicates a hard disk problem, but luckily I haven't seen this yet! :-) Error code 777 is largely obsolete now most people are on broadband, as an error code if your dial-up MODEM couldn't connect to the remote computer.