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27 Nov 2020, 13:20
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A cloud computing environment leverages many fundamental technologies. One such technology is virtualization, which allows for a number of virtual machines to share the physical resources of a single physical machine. A large number of physical machines with virtualization could be networked together to form what is known as a cloud environment. A virtual machine that is hosted on a physical machine is often referred to as a guest virtual machine.
The increase in the number of organizations using the same physical host machine for guest virtual machines creates opportunities for certain types of attacks. One example is a side channel attack, in which one virtual machine monitors how another uses shared processor memory to infer sensitive information.
A technique that allows a virtual machine to accommodate increased resource needs or protect against such attacks is migration. Migration is the process of moving a guest virtual machine from one physical host to another. Two migration types considered through experimentation were cloning migration and offline migration. To compare different migration types, a Denial of Service (DoS) scenario was created to increase the resource needs of a host and cause a migration of a virtual machine from one physical host to another.
The increase in the number of organizations using the same physical host machine for guest virtual machines creates opportunities for certain types of attacks. One example is a side channel attack, in which one virtual machine monitors how another uses shared processor memory to infer sensitive information.
A technique that allows a virtual machine to accommodate increased resource needs or protect against such attacks is migration. Migration is the process of moving a guest virtual machine from one physical host to another. Two migration types considered through experimentation were cloning migration and offline migration. To compare different migration types, a Denial of Service (DoS) scenario was created to increase the resource needs of a host and cause a migration of a virtual machine from one physical host to another.
For each of the following statements, select Yes if the statement accurately reflects the information provided. Otherwise, select No.
| Yes | No | |
| The fastest migration time recorded in the cloning migration tests was lower than the fastest time in the offline migration tests. | ||
| The median migration time was greater than the average for each of the two migration types. | ||
| The range of the offline migration times was more than twice the range of the cloning migration times. |
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Official Answer
The fastest migration time recorded in the cloning migration tests was lower than the fastest time in the offline migration tests.: No
The median migration time was greater than the average for each of the two migration types.: No
The range of the offline migration times was more than twice the range of the cloning migration times.: Yes
27 Nov 2020, 13:20
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Official Solution:
The fastest migration time recorded in the cloning migration tests was lower than the fastest time in the offline migration tests.
First, note that the scales on the two charts are not the same, so be careful not to compare the heights of the smallest bars directly. In the cloning migration tests, the fastest migration time was approximately 44.5 seconds. In the offline migration tests, the fastest time was about 21 seconds. Therefore, the statement is not accurate.
The median migration time was greater than the average for each of the two migration types.
The median of a list with an even number of values is the average of the fifth and sixth values when arranged in order. In the charts, this corresponds to the fifth and sixth migration times in sorted order. The average is represented by the blue line in both graphs.
In the cloning migration tests, the fifth and sixth values correspond to Tests 3 and 4, both of which are above the average line. Therefore, their average—the median—would also be greater than the average.
In the offline migration tests, all bars except the highest one are below the average line. This means the fifth and sixth values would also be below the average, so the median would be lower than the average.
Therefore, the statement is not accurate.
The range of the offline migration times was more than twice the range of the cloning migration times.
The range of the offline migration times is the highest time minus the lowest time, which is approximately 34 − 21 = 13 seconds. The range of the cloning migration times is about 49.5 − 44.5 = 5 seconds. Since 13 is more than twice 5, the statement is accurate.
Correct answer:
The fastest migration time recorded in the cloning migration tests was lower than the fastest time in the offline migration tests.
"No"
The median migration time was greater than the average for each of the two migration types.
"No"
The range of the offline migration times was more than twice the range of the cloning migration times.
"Yes"
Bunuel
The fastest migration time recorded in the cloning migration tests was lower than the fastest time in the offline migration tests.
First, note that the scales on the two charts are not the same, so be careful not to compare the heights of the smallest bars directly. In the cloning migration tests, the fastest migration time was approximately 44.5 seconds. In the offline migration tests, the fastest time was about 21 seconds. Therefore, the statement is not accurate.
The median migration time was greater than the average for each of the two migration types.
The median of a list with an even number of values is the average of the fifth and sixth values when arranged in order. In the charts, this corresponds to the fifth and sixth migration times in sorted order. The average is represented by the blue line in both graphs.
In the cloning migration tests, the fifth and sixth values correspond to Tests 3 and 4, both of which are above the average line. Therefore, their average—the median—would also be greater than the average.
In the offline migration tests, all bars except the highest one are below the average line. This means the fifth and sixth values would also be below the average, so the median would be lower than the average.
Therefore, the statement is not accurate.
The range of the offline migration times was more than twice the range of the cloning migration times.
The range of the offline migration times is the highest time minus the lowest time, which is approximately 34 − 21 = 13 seconds. The range of the cloning migration times is about 49.5 − 44.5 = 5 seconds. Since 13 is more than twice 5, the statement is accurate.
Correct answer:
The fastest migration time recorded in the cloning migration tests was lower than the fastest time in the offline migration tests.
"No"
The median migration time was greater than the average for each of the two migration types.
"No"
The range of the offline migration times was more than twice the range of the cloning migration times.
"Yes"
03 Apr 2025, 16:36
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This MSR question and its solutions have been completely revised and improved.
