Kerberos Question = Stale Tickets

[Brady, Ted]

We are implementing a conferencing platform for collaborative
conferencing and ran into an issue with authentication. A small group of
users were being challenged for domain authentication when trying to
access the conferencing platform from their Outlook calendars. As they
proceeded to enter their domain credentials there accounts were
'disabled'.
 
The vendor supporting the implementation effort has explained that this
behavior could be attributed to the Kereberos tickets becoming 'stale'
due to a prolonged time period in which the domain controllers were not
available.
 
I would like to better understand this explanation and also understand
what events could cause a ticket to become 'stale'.
 
Any support you can provide would be appreciated.
 
 
  
Thank you,
Ted Brady
JHU-APL
ITSD / ITC-1
Section Supervisor Voice Communications
240 228-0835 / 443 778-0835  Office
443 250-5220 Cell
ted.brady at jhuapl.edu