سوال ۱۷ کنکور ارشد علوم کامپیوتر ۱۴۰۰

PASSAGE 1: ADDRESSING (excerpt)

An applications program, with associated control software, resident in a node of a network, sending a message to a program elsewhere in the network may or may not know in which node its destination program is resident. To be more specific, a node is able to address a message to another physical node or to a logical node, a program resident in a node somewhere in the network. Physical addressing of a message may be to a node dedicated entirely to a specific application or it may be to a node with several applications resident. ... Logical or virtual addressing of a message is always to a program (a logical node) presumed to be resident in some node (unknown to the sender) of the network.

According to the passage, in logical or virtual addressing of a message to a program, ----------.

1. the sender only needs a virtual address
2. the program is always associated with a logical address
3. the sender has no need for program identification
4. the sender needs to know the location of the node in which the program resides