Question 8
Question: Which of the following best describes a direct benefit in using redundant routing on the Internet?
My Answer: Redundancy enables messages to be transmitted with as few packets as possible.
Why its incorrect: Redundancy on the Internet allows packets to be transmitted along multiple paths, but does not reduce the number of packets needed to transmit a particular message.
Correct Answer: Redundancy often allows messages to be sent on the network even if some network devices or connections have failed.
Why its correct: If a particular device or connection on the Internet fails, subsequent data will be sent via a different route, if possible. This is supported by redundancy in the network.
Question 14
Question: A list of numbers is considered increasing if each value after the first is greater than or equal to the preceding value. The following procedure is intended to return true if numberList is increasing and return false otherwise. Assume that numberList contains at least two elements.Which of the following changes is needed for the program to work as intended?
My Answer: n line 6, < should be changed to ≥.
Why its incorrect: By making this change, the procedure will immediately return true any time it encounters a value that is greater than or equal to the preceding value. It will not check any subsequent values in the list.
Correct Answer: Lines 8 and 12 should be interchanged.
Why its correct: As is, the procedure traverses numberList from left to right and returns true whenever it encounters a value that is less than the preceding value. If it never encounters such a value, false is returned. This has the effect of returning true whenever the list is not increasing and returning false whenever the list is increasing, which is the opposite of what is intended. By interchanging lines 8 and 12, the procedure will return true or false appropriately.
Question 19
Question: Which of the following best explains how devices and information can be susceptible to unauthorized access if weak passwords are used?
My Answer: Unauthorized individuals can deny service to a computing system by overwhelming the system with login attempts.
Why its incorrect: Overwhelming a system with requests in order to deny service can be done regardless of password strength.
Correct Answer: Unauthorized individuals can use data mining and other techniques to guess a user’s password.
Why its correct: A strong password is something that is easy for a user to remember but would be difficult for someone else to guess based on knowledge of that user. Weak passwords can often be guessed based on publicly available information about a user. Other weak passwords (such as “password” or “1234”) can often be guessed because they are commonly used.
Question 20
Question: A local router is configured to limit the bandwidth of guest users connecting to the Internet. Which of the following best explains the result of this configuration as compared to a configuration in which the router does not limit the bandwidth?
My Answer: The amount of time it takes guest users to send and receive large files is likely to decrease.
Why its incorrect: Limiting the bandwidth of a connection is likely to increase the amount of time it takes to send and receive files.
Correct Answer: Guest users will be restricted in the maximum amount of data that they can send and receive per second.
Why its correct: The bandwidth of a computer network is the maximum amount of data that can be sent in a fixed amount of time. With limited bandwidth, guest users will be restricted in the amount of data transmitted per second.
Question 21
Question: A video-streaming Web site keeps count of the number of times each video has been played since it was first added to the site. The count is updated each time a video is played and is displayed next to each video to show its popularity.
At one time, the count for the most popular video was about two million. Sometime later, the same video displayed a seven-digit negative number as its count, while the counts for the other videos displayed correctly. Which of the following is the most likely explanation for the error?
My Answer: The mathematical operations used to calculate the count caused a rounding error to occur.
Why its incorrect: This situation is consistent with the behavior of an overflow error, not a rounding error. A rounding error would lead to imprecision in the count, rather than increasing to the point of wrapping around to a negative number.
Correct Answer: The count for the video became larger than the maximum value allowed by the data type used to store the count.
Why its correct: This situation is consistent with the behavior of an overflow error. When the value of the count exceeded the maximum value that can be represented by a fixed number of bits, the count overflowed and wrapped around to a negative number.
Question 25
Question: Which of the following best describes the value returned by the procedure?
My Answer: The procedure returns the value of 2 * n.
Why its incorrect: The procedure does not return the value of 2 * n. For a procedure to return 2 * n, it could initialize result to 0 and then repeatedly add 2 to result a total of n times.
Correct Answer: The procedure returns the sum of the integers from 1 to n.
Why its correct: The procedure initially sets result to 1 and j to 2. In the REPEAT UNTIL loop, result is first assigned the sum of result and j, or 1 + 2. The value of j is then increased to 3. In each subsequent iteration of the loop, result is increased by each successive value of j (3, 4, 5, etc.) until j exceeds n. Therefore, the procedure returns the sum of the integers from 1 to n.
Question 32
Question: Which of the following best describes the value returned by the procedure?
My Answer: Public key encryption uses a single key that should be kept secure because it is used for both encryption and decryption.
Why its incorrect: Public key encryption uses a public key for encryption and a private key for decryption. Symmetric encryption is a method that uses a single key for both encryption and decryption.
Correct Answer: Public key encryption enables parties to initiate secure communications through an open medium, such as the Internet, in which there might be eavesdroppers.
Why its correct: Public-key encryption is considered a secure way of encoding data to prevent unauthorized access.
Question 33
Question: A company delivers packages by truck and would like to minimize the length of the route that each driver must travel in order to reach delivery locations. The company is considering two different algorithms for determining delivery routes.
My Answer: Algorithm II attempts to use an algorithmic approach to solve an otherwise undecidable problem.
Why its incorrect: The problem described is not undecidable, as it is possible to find an exact solution using algorithm I.
Correct Answer: Algorithm II uses a heuristic approach to provide an approximate solution in reasonable time.
Why its correct: lgorithm II runs in time proportional to , which is considered reasonable time because is a polynomial. This is considered a heuristic approach because it finds an approximate solution in reasonable time when the technique that finds an exact solution (algorithm I) does not run in reasonable time.
Question 36
Question: Individuals sometimes attempt to remove personal information from the Internet. Which of the following is the LEAST likely reason the personal information is hard to remove?
My Answer: There are potentially an extremely large number of devices on the Internet that may contain the information.
Why its incorrect: Personal information found online can be redistributed via social media posts, e-mail, and other methods. Through this redistribution, it can end up on a large number of devices.
Correct Answer: All personal information is stored online using authentication measures, making the information hard to access.
Why its correct: Personal information can be found in a variety of places where authentication measures may not be used, including social media sites. Personal information placed online can be collected, aggregated, distributed, and exploited.
Question 39
Question: A store uses binary numbers to assign a unique binary sequence to each item in its inventory. What is the minimum number of bits required for each binary sequence if the store has between 75 and 100 items in its inventory?
My Answer: 5
Why its incorrect: Using 5 bits will only allow for up to 32 sequences because 2^5 = 32.
Correct Answer: 7
Why its correct: Using 6 bits will only allow for up to 64 sequences because 2^6=64. Using 7 bits will allow for up to 128 sequences because 2^7 =128 Therefore, a minimum of 7 bits are needed.
Question 43
Question: Using 6 bits will only allow for up to 64 sequences because 2^6=64. Using 7 bits will allow for up to 128 sequences because 2^7 =128 Therefore, a minimum of 7 bits are needed.
My Answer: A user receives an e-mail that claims to be from the user’s bank. The e-mail instructs the user to click on a link to a Web site and enter a username and password to verify an account. Shortly after following the steps, the user discovers that the Web site is fraudulent and that the user’s username and password were stolen.
Why its incorrect: This is an example of phishing. While phishing may enable an unauthorized user to gain access to a computer system, it is not an example of keylogging.
Correct Answer: A user unintentionally installs a program on their computer that records all user input and forwards it to another computer. A few weeks later, someone else is able to access the user’s computer using the recorded data.
Why its correct: Keylogging is the use of a program to record every keystroke made by a computer to gain fraudulent access to passwords and other confidential information.
Question 63
Question: Which of the following expressions are equivalent to the value of expression as shown in the table?
My Answer: (NOT input1) AND (NOT input2)
Why its incorrect: When input1 is true and input2 is false, then (NOT input1) will be false and (NOT input2) will be true. Therefore, (NOT input1) AND (NOT input2) will be false instead of the intended value true.
Correct Answer: A + D
Why its correct: When input1 and input2 are both true, the expression (input1 AND input2) is true, so NOT (input1 AND input2) will evaluate to false. In all other cases, (input1 AND input2) will evaluate to false, so NOT (input1 AND input2) will evaluate to true.