New
#11
The computers will be connected together on a network created either by a router or by a server. In a small business, more likely just a router. The computers are not daisy chained together. Token ring networks where the network ran in a circle from one computer to the next became obsolete in the early 2000's. The vast majority of networks today are hub and spokes with the central hub being either a server or a router.
The NAS just attaches to the network like any one of the computers do and gets an IP address. It shows up as a disk drive and gets written to and read from either through it's IP address, or the IP address can be mapped to an actual drive letter on the computers. Then either important files are kept on the NAS, and/or backup images of the computers are stored on the NAS. Most NAS boxes also have processors so they can act as application or media servers as well.
If the NAS is configured as RAID 1, it will have at least 2 physical hard drives in it and the NAS enclosure will mirror all the drives to each other so each physical drive is an exact copy of all the other drives in the enclosure. This provides redundancy. If one drive fails, simply replace it and the RAID 1 controller will automatically copy the contents of one of the good remaining drives to the new drive re-establishing the mirror. There are other RAID modes that offer redundancy as well, but RAID 1 is the simplest.
If one of the computer's fails, then once it is repaired, it is booted from a repair drive such as a USB flash drive or DVD. The repair software will connect the computer to the network and restore the backup image stored on the NAS back to the newly repaired computer and it picks up from the point in time when the backup was created.