By default, Multisite WordPress installs are backed up the same way regular, single-site WordPress installs are — that is, a full copy of the entire network’s database is made.
Check out Our Backup Process article for more details on this process, including how to extend our 14-day retention policy, and where to access your backups.
If you are looking for individual sub-site backups in an incremental fashion, we have a unique process that allows us to cleave your sites so they can be backed-up and restored independently of one another.
Note: While this is not a standard feature, this solution can be configured by contacting support and requesting ‘independent sub-site backups’.