In the operation of a website, the web server anticipates that the HTTP data stream dispatched by the client, such as a user’s web browser or the CheckUpDown robot, will contain a ‘Content-Length’ specification. Generally, this specification is applied in scenarios involving HTTP methods that lead to data being stored on the web server. It’s not commonly associated with methods used for extracting data from the server. Thus, when the server receives a data stream from a client, it expects to see this ‘Content-Length’ detail, especially in situations where data is being uploaded or modified on the server.
Fixing 411 errors – general
In the vast majority of web traffic, encountering this error is uncommon, especially when the client system is a web browser. To resolve this issue, a thorough examination of the client system’s actions is necessary. Understanding what the client system is attempting to do is crucial. Following this, a discussion with the Internet Service Provider (ISP) is required to ascertain why the web server is expecting a ‘Content-Length’ specification. This two-step process of analysis and communication is key to addressing and solving the problem.
Fixing 411 errors – CheckUpDown
The service diligently watches over user sites for various HTTP errors, including error 411. Such an error is unexpected in a user’s CheckUpDown account. If it does occur, it often signals a flaw in either the programming of the service’s systems or that of the web server overseeing the site. Specifically, the ‘Content-Length’ specification, a focal point of this error, does not align with the method employed by the service when examining URLs.
Users encountering a 411 error are urged to contact the service, with a preference for communication via email. In these situations, users are typically unable to resolve the issue independently. Therefore, the service team must collaborate with the user’s Internet Service Provider (ISP) and the vendor of the web server software. This joint effort is crucial to pinpoint the precise cause of the error and formulate an effective resolution strategy.
411 errors in the HTTP cycle
Whenever a client, such as a web browser or the CheckUpDown robot, initiates communication with a web server, it follows a distinct sequence of steps. The process begins with the client deriving the IP address from the site’s URL, discarding the initial ‘http://’. This task of transforming the IP name into an IP address is handled by domain name servers (DNS).
The next phase involves establishing an IP socket connection to the obtained IP address. Through this connection, the client then transmits an HTTP data stream to the web server. In turn, the web server responds with its own HTTP data stream. This stream is laden with various status codes, the significance of which is defined by the HTTP protocol. The client’s job is to analyze this stream, extracting status codes and other relevant data.
The error under discussion, identified as ‘411’, emerges in this final stage. It occurs when the client discerns the ‘411’ status code within the HTTP data stream received from the web server. This particular code indicates a specific communication issue between the client and the server.
