問62
頻出度★★☆
電子メールに関するプロトコルの説明のうち, 適切な記述はどれか。
平成28年度 春期 ITパスポート試験 問62
テクノロジ系ネットワーク › 通信プロトコル
This question's explanation and your answers so far.
解説
問 62
Incorrectア
Converting binary data such as images into an ASCII character string so it can be sent by email is the role of MIME (encoding such as Base64), not a function of IMAP4. IMAP4 is a protocol for receiving and viewing mail on the server, so the description is incorrect.
Incorrectイ
POP3 is a protocol for receiving email from a mail server and cannot be used to send email from a PC. Sending is handled by SMTP, so the description is incorrect.
- ウ
正解 The correct answer is ウ. POP3 (Post Office Protocol version 3) and IMAP4 (Internet Message Access Protocol version 4) are both protocols used by the receiving-side client, such as the user's PC, to receive (retrieve) email that has arrived at the mail server. POP3 downloads mail from the server and manages it locally, while IMAP4 keeps mail on the server for viewing and management; despite this difference, both share the property of being used for receiving. Therefore the statement “POP3 or IMAP4 makes it possible to receive email from a mail server” is correct.
Incorrectエ
SMTP (Simple Mail Transfer Protocol) is a protocol for sending and forwarding email and has no function to encrypt the message body. Encryption is handled by S/MIME, PGP, or TLS on the communication channel, so the description is incorrect.
ここがポイント
- The division of roles among the main email protocols: SMTP for sending and forwarding, POP3 and IMAP4 for receiving (retrieving). Also note the difference that POP3 is the download type while IMAP4 is the server-storage and viewing type.
- Distinguish that binary-to-text conversion (such as Base64) is handled by MIME, and encryption by S/MIME, TLS, and the like — these are not functions of SMTP/POP3/IMAP4 themselves.
用語