Which of the following NIS clients returns the name of the NIS server used by the NIS client? A. ypwhich B. ypbind C. ypcat D. yppoll E. None of the above

The correct answer is A. ypwhich.

ypwhich is a command-line utility that returns the name of the NIS server used by the NIS client. It is used to determine the NIS server that is currently being used by the client.

ypbind is a daemon that binds a client to an NIS server. It is used to establish a connection between the client and the server.

ypcat is a command-line utility that prints the contents of an NIS map. It is used to view the contents of an NIS map.

yppoll is a command-line utility that polls an NIS server for changes. It is used to check for changes to an NIS map.

E. None of the above is incorrect because ypwhich is the only command-line utility that returns the name of the NIS server used by the NIS client.