There are two types of auto-replenishment, both of which are activated by default for all properties.
Normal auto-replenishment puts cancelled rooms back up for sale on Booking.com. However, if a property closes availability for that date, cancelled rooms will not be put back on sale. This is a setting that cannot be deactivated.
Aside from that, there is also a ‘Reopen closed rooms’ setting, which is also active by default – but which can be deactivated on request. When this setting is active, rooms are auto-replenished regardless of whether the property has closed availability on that date.
For more information on auto-replenishment and how it works, read our introduction to auto-replenishment.