Performance Monitor includes counters that display the number of anonymous and non-anonymous connections to each IIS service. These counters are included in the HTTP Service, FTP Server, and Gopher Service performance objects. The term non-anonymous is used instead of authenticated to account for custom authentication schemes that require data from the client other than, or in addition to, the user name and password.
By themselves, these Performance Monitor counters help you determine the number and proportion of each type of connection. You can also use the counter values to project the estimated effect of changing how you handle anonymous and non-anonymous users. For example, if the vast majority of connections are anonymous, prohibiting anonymous connections has a more significant impact than if most connections are non-anonymous.
Combining data from these counters with general measures of server performance, such as data on processor time, the processor queue, memory, disk reads and writes, and throughput, is even more useful. Using the combined data, you can associate varying numbers and proportions of anonymous and non-anonymous users with their effect on the performance of system components.