In the left panel, select Last Validated Not Within, Not Active Within, or one of the other filters, and select the date range.
Last Validated filters users by the Last Validated date. Users without a Last Validated date have never validated in VIP.
Active Within filters users by the last time any change was made to the record for that user. This includes updates by LDAP sync updates, SSP/MyVIP login attempts, IA or Device fingerprint activity, Last Validated, etc.