In the system of Exercise 14.4it is required to synchronize a file server’s clock to within ±1
millisecond. Discuss this in relation to Cristian’s algorithm.
What will be an ideal response?
To synchronize a clock within ± 1 ms it is necessary to obtain a round-trip time of no more than 18 ms, given
the minimum message transmission time of 8 ms. In principle it is of course possible to obtain such a round
trip time, but it may be improbable that such a time could be found. The file server risks failing to synchronize
over a long period, when it could synchronize with a lower accuracy.
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What is the purpose of the finally block?
What will be an ideal response?
(Turtle Graphics) The Logo language, which is popular among elementary school children, made the concept of turtle graphics famous. Imagine a mechanical turtle that walks around the room under the control of a C++ program. The turtle holds a pen in one of two positions, up or down. While the pen is down, the turtle traces out shapes as it moves; while the pen is up, the turtle moves about freely without writing anything. In this problem, you’ll simulate the operation of the turtle and create a computerized sketchpad as well. Use a 20-by-20 array floor that is initialized to false. Read commands from an array that contains them. Keep track of the current position of the turtle at all times and whether the pen is currently up or down. Assume that the turtle always starts at position (0, 0) o
Suppose that the turtle is somewhere near the center of the floor. The following “program” would draw and print a 12-by-12 square and end with the pen in the up position:
2
5,12
3
5,12
3
5,12
3
5,12
1
6
9
As the turtle moves with the pen down, set the appropriate elements of array floor to true. When the 6 command (print) is given, wherever there is a true in the array, display an asterisk or some other character you choose. Wherever there is a zero, display a blank. Write a program to implement the turtle graphics capabilities discussed here. Write several turtle graphics programs to draw interesting shapes. Add other commands to increase the power of your turtle graphics language.
Explain the rules that apply to using domain names.
What will be an ideal response?
The computer handling incoming e-mail messages is known as the ____________________ e-mail server.
Fill in the blank(s) with the appropriate word(s).