COMPUTER NETWORKS AND COMMUNICATIONS
NETWORK TOPOLOGIES AND PROTOCOLS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Transport Layer
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Data Link Layer
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Application Layer
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Network Layer
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Detailed explanation-1: -SMTP is an application layer protocol that is used to transmit electronic mail. The SMTP sender process uses a randomly assigned TCP port above 1023 to send SMTP messages to the SMTP receiver process that is listening at the well-known TCP port 25.
Detailed explanation-2: -As with the other protocols and services discussed in this section, SMTP operates at the Application layer and relies on the services of the underlying layers of the TCP/IP suite to provide the actual data transfer services.
Detailed explanation-3: -A few examples of application layer protocols are the Hypertext Transfer Protocol (HTTP), File Transfer Protocol (FTP), Post Office Protocol (POP), Simple Mail Transfer Protocol (SMTP), and Domain Name System (DNS). The presentation layer prepares data for the application layer.
Detailed explanation-4: -SMTP is an application layer protocol (layer 7).
Detailed explanation-5: -SMTP is used to send and receive email. It is sometimes paired with IMAP or POP3 (for example, by a user-level application), which handles the retrieval of messages, while SMTP primarily sends messages to a server for forwarding.