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The Application Layer

The Application Layer. Chapter 7. DNS – The Domain Name System. The DNS Name Space Resource Records Name Servers. The DNS Name Space. A portion of the Internet domain name space. Resource Records. The principal DNS resource records types. Resource Records (2).

daniel-potts
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The Application Layer

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  1. The Application Layer Chapter 7

  2. DNS – The Domain Name System • The DNS Name Space • Resource Records • Name Servers

  3. The DNS Name Space A portion of the Internet domain name space.

  4. Resource Records The principal DNS resource records types.

  5. Resource Records (2) A portion of a possible DNS database for cs.vu.nl.

  6. Name Servers Part of the DNS name space showing the division into zones.

  7. Name Servers (2) How a resolver looks up a remote name in eight steps.

  8. Electronic Mail • Architecture and Services • The User Agent • Message Formats • Message Transfer • Final Delivery

  9. Electronic Mail (2) Some smileys. They will not be on the final exam :-).

  10. Architecture and Services Basic functions • Composition • Transfer • Reporting • Displaying • Disposition

  11. The User Agent Envelopes and messages. (a) Paper mail. (b) Electronic mail.

  12. Reading E-mail An example display of the contents of a mailbox.

  13. Message Formats – RFC 822 RFC 822 header fields related to message transport.

  14. Message Formats – RFC 822 (2) Some fields used in the RFC 822 message header.

  15. MIME – Multipurpose Internet Mail Extensions Problems with international languages: • Languages with accents (French, German). • Languages in non-Latin alphabets (Hebrew, Russian). • Languages without alphabets (Chinese, Japanese). • Messages not containing text at all (audio or images).

  16. MIME (2) RFC 822 headers added by MIME.

  17. MIME (3) The MIME types and subtypes defined in RFC 2045.

  18. MIME (4) A multipart message containing enriched and audio alternatives.

  19. Message Transfer Transferring a message from elinore@abc.com to carolyn@xyz.com.

  20. Final Delivery (a) Sending and reading mail when the receiver has a permanent Internet connection and the user agent runs on the same machine as the message transfer agent. (b) Reading e-mail when the receiver has a dial-up connection to an ISP.

  21. POP3 Using POP3 to fetch three messages.

  22. IMAP A comparison of POP3 and IMAP.

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