Four dates drive the event:

• Start Date and End Date - when the event runs.
• Registration Open Date - registration is not possible before this date.
• Registration Close Date - the last day of normal registration.
• Late Registration Close Date - only if you allow late registration.

Closing dates run to the end of that day, not to midnight at its start. A close date of 14 March means registration is open all day on the 14th and shuts at 11:59:59 pm.

All of this is measured in the Time Zone you set on the event, not the registrant's zone and not the server's. Set it correctly or your deadlines will land at the wrong moment for everyone.