Server variables are a type of persistent variable. Server variables are specific to the server on which they are created and are stored in that server's random-access memory (RAM) memory.
As with our other variables types that are stored in memory, creating or reading server variables from memory can lead to memory corruption and server instability. To access server variables, you should properly apply a CFLOCK tag around the variable access.
As mentioned, server variables are persistent, but they are also specific to the server on which they are set and exist until the ColdFusion Server is restarted, unless they are specifically deleted from the structure.
To access the server structure, use the CFDUMP tag, as follows:
There are different predefined server variables that refer to the ColdFusion installation on the server and to the server's OS. They are listed in Table 8.2.