Why might a mount point show old content instead of the real one?

Question

linux

/etc/fstab specifies the mounting of a Windows-shared folder:

//Server/Update /mnt/srv_update cifs username=guest,password=,iocharset=utf8,file_mode=0777,dir_mode=0777,vers=2.1 Mounted

at some point the shared folder began to show some old cache instead of real content.

Remounting helped (mount -a). But what was it?

How now to live with the feeling that the shared folder (its relevance) cannot be trusted?

Answer 1

And at that moment it was definitely mounted? Maybe someone unmounted it manually and there is just local content - unmount it and see what is in the local folder - if the same "hash" means it just wasn't mounted at that moment