Every time you browse to a website, the server sends back a status code, telling the browser what to do.  It can signal the browser to go somewhere else, like a cop directing traffic.  These codes can signal that there was an error with the server and the file couldn’t be accessed.  They can also signal invalid permissions, because of an invalid password.  We’re gonna cover a few of the common server status codes today in the 1xx, 2xx, and 3xx range today.

Here is a table about the basics of what the codes are for:

1xx

Informational

2xx

Success

3xx

Redirection

4xx

Client Error

5xx

Server Error

 

100 Range Status Codes
These really aren’t used anymore, except to tell the computer to keep on doing what it’s doing.  It’s more of a “carry on”, but they’re not used anymore, so we won’t discuss them too much.

200 Range Status Codes
The most common response code on the internet is 200 – OK.  It tells the requesting computer that everything went alright, and the file was properly served.

status200

The next common 200 range status code is 203.  This is found mostly on proxy services where everything went alright, however the content that your computer is receiving is NOT what the server originally sent, meaning the third party has changed some of the content.  This is when you use a proxy and they add branding to the bottom of the page, or something like that.

204 is a common code meaning everything went okay, however the file returned was empty, so there was no data to return.  This may be because the file was left accidentally empty or because the file wasn’t needed for the page returned, and an empty file was returned.

status204

Finally, to wrap up the 2xx range, there is 206.  This is a partial file, usually because a download is paused or interrupted.  This can also be because only a part of the file is needed and the server knows ahead of time which part that file is.  It is not very common, but if it’s encountered on your web server, it is worth investigating the cause.

300 Range Status Codes
301 is the most common 300 status code, which is for a permanent redirect.  This is commonly used to transfer traffic from a non-www URL to www, or transfer from http to https.  This is commonly used for SEO because search engines see www and non-www traffic as two separate sites, and your site may lose standing for having duplicate traffic.  This is an extremely important status code to understand because of all that it can accomplish.  It can also redirect mobile traffic to a mobile subdomain or folder for sites that are optimized.

status301

304 is another common status, which basically tells the client that there was another version of the file that was available in cache, and that there was no change, so the client will be receiving the old version.  This can greatly speed up traffic on your site because some items, like images or CSS files may not change that much, so there is no point in serving a new copy of the file, when a cached version is available.

status304

 

This wraps up today’s little post on some of the common HTTP status codes.  Learning how these interact with clients and servers can help you troubleshoot issues and make your servers run more efficiently.  JadeServe can help if issues crop up, or you get errors you don’t understand.

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