UNIVERSITY OF CALIFORNIA, DAVIS
BERKELEY
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DAVIS
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IRVINE
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LOS ANGELES
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RIVERSIDE
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SAN DIEGO
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SAN FRANCISCO
SANTA BARBARA
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SANTA CRUZ
EEC 173A/ECS 152A-Computer Networks
Spring 2020
Homework #4 (due 11:59 pm, May. 22, 2020)
Total: 100 points
1.(30 points)General Questions.(a)(5 pt.) What information is used by a process running on one host to identify a process running on another host? (b)(5 pt.) Suppose you wanted to do a transaction from a remote client to a server as fast as possible. Would you use UDP or TCP? Why? (c)(5 pt.) Why do HTTP, SMTP, and POP3 run on top of TCP rather than UDP? (d)(5 pt.) In BitTorrent, suppose Alice provides chunks to Bob throughout a 30-second interval. Will Bob necessarily return the favor and provide chunks to Alice in the same interval? Why or Why not? (e)(5 pt.) The UDP server described in the Textbook needed only one socket, whereas the TCP server needed two sockets. Why? If the TCP server were to support n simultaneous connections, each from a different client host, how many sockets would the TCP server need? (f)(5 pt.) How does SMTP mark the end of a message body? How about HTTP? Can HTTP use the same method as SMTP to mark the end of a message body? Explain.
