for its IP address and the location of its operating system boot files BOOTP sends a UDP message with a subnetwork broadcast address and waits for a reply from a server that gives it the IP address. The same message might contain the name of the machine that has the boot files [...]

DNS uses UDP for communication between servers. It is a better choice than TCP because of the improved speed a connectionless protocol offers. Of course,
transmission reliability suffers with UDP.

A resource record is an entry in a name server’s database. There are several types of resource records used, including name-to-address resolution information. Resource
records are maintained as ASCII files.

External Data Representation is a method of encoding data within an RPC message, used to ensure that the data is not system-dependent.

The Mount protocol returns a file handle and the name of the file system in which a requested file resides. The message is sent to the client from the server after reception of a client’s request.

What advantage does REX offer other similar utilities

A pseudo tty or false terminal enables external machines to connect through Telnet or rlogin. Without a pseudo tty, no connection can take place.

Anonymous FTP enables users to connect to a host without using a valid login and password. Usually, anonymous FTP uses a login called anonymous or guest, with the
password usually requesting the user’s ID for tracking purposes only. Anonymous FTP is used to enable a large number of users to access files [...]