When reading this document you need to know some context i which I use the nas DNS-323. And in this section I explain it.

I have a local network at my home. Its ip is 172.31.1.0/24. The DNS-323 is named as nas1 and has ip 172.31.1.21. I note the nas1 name in my hosts file, and thus I'm able to access it as a nas1 instead of 172.31.1.21.

my-computer # grep nas1 /etc/hosts
172.31.1.21     nas1

My computer have the ip 172.31.1.8.

I have this device for archiving my data and for that reason I use RAID-1 (mirroring) configuration. I do not want to lost my data. Because of this there are two identical hard disc in the box. I buy 1TB WD disc from the RAID edition. THe are not so cheap as others, but my data are more pricey and I want have them safe.