Two questions about NIS

Two questions about NIS-general Linux technology-Linux technology and application information. The following is a detailed description. I would like to ask, that is, another step during the NIS experiment.
I:
[Root @ test root] # nisdomainname
What is the role of this step? Can I skip this step? Do I need to perform this step every time I start the system?

II:
[Root @ test root] #/usr/lib/yp/ypinit-m
At this point, we have to construct a list of the hosts which will run NIS servers. server. cluster is in the list of NIS server hosts. please continue to add the names for the other hosts, one per line. when you are done with the list, type . Next host to add: server. cluster
Next host to add: <= click [ctrl + d] to jump out.

In this step, I want to ask: how can I change the computer name?
In addition, where can I delete the database created in this step?
Thank you.