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HW1.pdf
Homework 1
UT EID: XXX999, UTCS username: XXXXXXXX
CS326e, Spring 2014, Dr. P. Cannata
Department of Computer Science, The University of Texas at Austin --
Problem 6
a) d prop = m / s seconds.
b) d trans = L / R seconds.
c) d end −to−end = (m / s + L / R) seconds.
d) The bit is just leaving Host A.
e) The first bit is in the link and has not reached Host B.
f) The first bit has reached Host B.
g) Want
L
120
m= s=
2.5 × 10 8 = 536 km.
3
R
56 × 10
(
Problem 19
An example solution:
)
Traceroutes from two different cities in France to New York City in United States
a) In these traceroutes from two different cities in France to the same destination host in
United States, seven links are in common including the transatlantic link.
b) In this example of traceroutes from one city in France and from another city in
Germany to the same host in United States, three links are in common including the
transatlantic link.
Traceroutes to two different cities in China from same host in United States
c) Five links are common in the two traceroutes. The two traceroutes diverge before
reaching China
72800 IN
NS
C.GTLD-SERVERS.NET.
Among all returned edu DNS servers, we send a query to the first one.
dig +norecurse @E.GTLD-SERVERS.NET any gaia.cs.umass.edu
umass.edu.
umass.edu.
umass.edu.
172800 IN
172800 IN
172800 IN
NS
NS
NS
ns1.umass.edu.
ns2.umass.edu.
ns3.umass.edu.
Among all three returned authoritative DNS servers, we send a query to the first one.
dig +norecurse @ns1.umass.edu any gaia.cs.umass.edu