Server response code (HTTP CODE)

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When checking a page, search engine programs first look at the server response code, and then proceed to check the document content. There are special services to monitor the online status of a site and assess site accessibility. One of these services is the BAILRY service – a free regular (periodic) website accessibility check. This service also has a paid subscription for constant monitoring of site availability.

The server response code (HTTP CODE) is a three-digit number that the server gives to a browser request. The number may be followed by a brief explanation of the code in English (instructions for the user when visiting a page or document on the site). To check the server response code of your website page, you can use a service where, if you follow a link, you can determine the server response code.

State classes – these are groups of codes united by certain characteristics. The class of the condition is indicated by the first digit in the code. There are five classes:

1xx — information codes. They are responsible for the data transfer process. These are temporary codes; they indicate that the request has been accepted and processing will continue.

2xx — successful processing. The request was received and successfully processed by the server.

3xx — redirection (redirect). These server responses indicate that further action must be taken to complete the request. For example, make a request to a different address.

4xx — user error. This means that the request cannot be completed due to his fault.

5xx — server error. These codes occur due to errors on the server side. In this case, the user did everything correctly, but the server cannot fulfill the request. For codes of this class, the server must display a message that it cannot process the request and for what reason.

Basic server responses

200 ОК – the most popular and important status. It means that the request was completed successfully as expected by the user – the requested data or page exists and is viewable. All pages that we want to see in the search engine index must return the code 200 OK.

301 Moved Permanently – this answer states that the document or page has been moved to another address permanently. If a page that was already in search engine results has changed its address, it is recommended to set up a 301 redirect from the old URL to the new one to save traffic and link juice.

302 Found – the document has been temporarily moved to another address.

304 Not Modified – important code in terms of server load and amount of data transferred. The server returns a 304 code if the last update date (Last-Modified) in the HTTP header is older than the date in the request with the If-Modified-Since header. That is, if the document has not changed since the specified date, the server returns code 304 Not Modified. In this case, the search engine does not need to re-upload the document – it has not changed since its last visit.

403 Forbidden – access denied. This response is returned if the user is denied access to this document. In this case, we are not talking about HTTP authentication (401 and 407 codes are used for such cases). The 403 code is displayed, for example, when logging in from prohibited IPs or trying to view the system .htaccess file.

404 Not Found – probably every user has come across this answer. It means that nothing was found at this URL – the document does not exist.

410 Gone – this response says that the document has been permanently deleted and is no longer available.

451 Unavailable For Legal Reasons – lately this code has become more common. It means that access to the server is blocked due to a ban at the state level or by a court decision in case of copyright infringement. Error 451 is a clarifying version of the 403 code.

500 Internal Server Error – this is any internal server error that is not described in other errors of this class. It occurs if the server encounters a problem that prevents the request from being completed. For example, this error may occur due to errors in setting the configuration file.

503 Service Unavailable – the server is temporarily unable to process requests due to technical reasons. If the server receives too many requests and is unable to handle them, this is the response we will see.

504 Gateway Timeout – the gateway is not responding. The response appears if the server was acting as a proxy and did not wait for a response from the upstream server to complete the request.

Finally, it is important to note that the trust of clients and users in your website, as well as your position in search engines, directly depend on the availability of your resource (website) at any given time. And you can control this availability using the BAILRY service – a unique software product that has no analogues on the market. To stay informed, sign up for a free regular (periodic) website accessibility check today!