It is possible to put a custom login page up for the Serv-U login screen. When this happens, the page is most likely not displaying the version number. One way that may help identify the version is to visit the Mobile login page at /Web Client/Mobile/MLogin.htm.
Why is this important?
When performing external security scans with tools like Nessus, it may report that the version of Serv-U is incorrect. Finding the version number is important in identifying potential false positives.