We are located in the Huygens building, room number HG03.055. The entrance is in the main 'street' on the 3rd floor, next to corridor 5 across the elevators.
C&CZ can usually be reached on working days from 8.30 till after 18.00 hour. Normally, the general helpdesk number will always be answered during these hours.
According to an international rule, every Internet-domain must have a "postmaster", who regularly reads mail addressed to him/her. You can ask this fictitious person any question related to mail. C&CZ uses this mail address also for all kinds of procedures, related to computer usage in the Faculty of Science, like requesting a new login, removing a login or changing disk quota.
The persons behind 20000 and postmaster change regularly.