In this chapter we have examined the characteristics of the TCP and UDP protocols, which implement transport in the TCP/IP stack. In addition, we have examined how these protocols underlie higher-level application protocols such as SMTP and HTTP. Without reliable delivery provided by TCP and lightweight delivery provided by UDP, application protocols would be unable to function.
1. | What is the purpose of the DATA command?
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2. | What is the purpose of the EHLO command?
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3. | What is the purpose of the EXPN command?
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4. | What is the purpose of the HELO command?
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5. | The QUIT command is used for what purpose?
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6. | The RCPT command is used for what purpose?
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7. | The VRFY command is used for what purpose?
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8. | The MAIL command is used for what purpose?
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9. | What is the correct description of the HTTP code 200?
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10. | What is the correct description of the HTTP code 201?
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11. | What is the correct description of the HTTP code 202?
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12. | What is the correct description of the HTTP code 203?
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13. | What is the correct description of the HTTP code 204?
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14. | What is the correct description of the HTTP code 205?
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15. | What is the correct description of the HTTP code 206?
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Answers
1. | A. The DATA command indicates that the data being sent is message data. |
2. | B. The EHLO command indicates that the host speaks ESMTP. |
3. | C. The EXPN command lists local members of a mailing list. |
4. | D. The HELO command indicates that the host speaks SMTP. |
5. | B. The QUIT command ends a session. |
6. | C. The RCPT command contains the address of the recipient. |
7. | D. The VRFY command verifies that a recipient address exists as a user account on the system. |
8. | A. The MAIL command contains the address of the sender. |
9. | A. The HTTP code 200 indicates OK. |
10. | B. The HTTP code 201indicates Created. |
11. | C. The HTTP code 202 indicates Accepted. |
12. | D. The HTTP code 203 indicates Non-Authoritative Information. |
13. | A. The HTTP code 204 indicates No Content. |
14. | B. The HTTP code 205 indicates Reset Content. |
15. | C. The HTTP code 206 indicates Partial Content. |