sudo and password time buffer

Dear all ! I have a little problem with sudo : when I do not use the NOPASSWD: directive, the user which light use sudo is only asked once for a password. Afterwards, even after logging out, he may enter commands without typing a password. I have heard that sudo implements a kind of "time buffer", that sayd a duration within which it remembers the password of a user. Is it possoble to somehow disable that grace period ? Thanks a lot in advance for any information Kind regards, Gerd -- Gerd-Christian Michalke gmichalk@freegates.be \\_// +32 2 / 376 43 36 (. .) Do you Linux ? --------------------------------------oOOo-oOOo----------------------