What does the HTTP monitor metric 'Waiting' measure?

The metric 'Waiting' in an HTTP monitor specifically measures the time until the first byte is received from the server, commonly known as TTFB (Time to First Byte). This metric is critical as it gives insight into how quickly a server starts to respond after receiving a request. A lower waiting time generally indicates that the server is processing requests efficiently and is capable of delivering content quickly to the user.

Understanding this metric is essential for performance tuning, as it helps identify issues related to server processing or back-end delays affecting user experience. If the 'Waiting' time is high, it suggests that there may be delays in how the server is preparing data, which could lead to optimization opportunities.

In contrast, the other metrics provided are focused on different aspects of HTTP requests. The time taken until the server starts receiving a request pertains to the network delay before the server begins processing. The time taken for all data to be downloaded measures the overall transmission of data after the response begins. The overall response time accounts for all phases of the request and response lifecycle, which includes both waiting time and the time for data transfer post-response initiation. Thus, they reflect broader or different aspects of HTTP performance rather than the specific metric of 'Waiting'.