When a synthetic web test is configured, probes and endpoint agents will attempt to connect to the target URL(s) and download any content. In the process of doing so, several metrics about this HTTP/HTTPS transaction are collected.
Each target URL will be tested once every 5 minutes and the following metrics are collected for each test run:
- Availability is the number fo successful transactions expressed as a percentage. A transaction is considered successful if no connection errors were encountered and the HTTP return code started with a 2 or a 3 (e.g. 200, 302, etc).
- DNS Lookup is the time taken, in msec, to complete the DNS resolution of the target URL's domain.
- TCP Handshake is the time taken, in msec, to complete the TCP 3-way handshake/connection establishment.
- SSL Handshake is the time taken, in msec, to complete the SSL handshake and establish a secure connection between the client and the server.
- Waiting is the time taken, in msec, for the server to process the HTTP request and send the first part of the response back.
- Data Transfer is the time taken, in msec, to receive all of the data from the server.
- Time To First Byte is the time taken, in msec, from the start of the DNS lookup to receive the 1st byte of data from the server. It is effectively the same as DNS Lookup + TCP Handshake + SSL Handshake + Waiting.
- Total Time is the total time, in msec, of the entire transaction. It is effectively the same as DNS Lookup + TCP Handshake + SSL Handshake + Waiting + Data Transfer.
- Wire Size is the total amount of data downloaded, in bytes, from the server (excluding any headers).
- Throughput is the average download speed, in bps, of the data downloaded from the server (excluding any headers). It is effectively (8 X Wire Size) / (1000 X Data Transfer Time)