TCP IP Illustrated

Weve also looked at newer extensions for all three

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Unformatted text preview: /plain SEND rfcl479.txt --OtherAccess Content-Type: Message/External-body; name="rfcl479.txt"; site="ds.internic.net", access-type="anon-ftp"; directory="rfc" Content-Type: text/plain --OtherAccess-the final boundary --NextPart-Figure 28.8 Example of a MIME multipart message. This section has been a brief overview of MIME. For additional details and examples of MIME, see RFC 1521 and [Rose 1993]. 28.5 Summary Electronic mail involves a user agent at both ends (the sender and receiver) and two or more message transfer agents. We can divide a mail message into three parts: the envelope, the headers, and the body. We've seen how all three parts are exchanged using SMTP, the Internet standard. All three are exchanged as NVT ASCII characters. We've also looked at newer extensions for all three parts: extended SMTP for the envelope, non-ASCII headers, and the addition of structure to the body using MIME. The structure and encoding used by MIME allow arbitrary binary data to be exchanged, using existing 7-bit SMTP MTAs. Exercises 28.1 Read RFC 822 to find out what a domain literal is. Try sending mail to yourself using one. 28.2 Excluding the connection establishment and termination, what is the minimum number of network round trips to send a small mail message? 28.3 TCP is a full-duplex protocol, yet SMTP uses TCP in a half-duplex fashion. The client sends a command then stops and waits for the reply. Why doesn't the client send multiple commands at once, for example, a single write that contains the HELO, MAIL, RCPT, DATA, and QUIT commands (assuming the body isn't too large)? file:///D|/Documents%20and%20Settings/bigini/Doc...omenet2run/tcpip/tcp-ip-illustrated/smtp_sim.htm (22 of 23) [12/09/2001 14.47.52] Chapter 28. SMTP: Simple Mail Transfer Protocol 28.4 How can this half-duplex operation of SMTP fool the slow start mechanism when the network is running near capacity? 28.5 When multiple MX records exist with the same preference value, should they always be returned by a name server in...
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This test prep was uploaded on 04/04/2014 for the course ECE EL5373 taught by Professor Guoyang during the Spring '12 term at NYU Poly.

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