hw4_soln.pdf - UNIVERSITY OF CALIFORNIA DAVIS BERKELEY...

UNIVERSITY OF CALIFORNIA, DAVIS
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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
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SANTA BARBARA
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SANTA CRUZ
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EEC 173A/ECS 152A-Computer Networks Winter 2019
Solution for Homework #4
Total: 100 points
1. (30 points) Review 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?
You would use UDP. With UDP, the transaction can be completed in one roundtrip time
(c) (5 pt.) Why do HTTP, FTP, 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 Section 2.8 of the TextBook needed only one socket,
whereas the TCP server describd in Section 2.7 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?