Computer Science Semester Exam

Fill out the truth table for the circuit by entering a 0 or 1 in the output column for each row:

1,0,0,0

Using the ASCII table above write the word HELLO in binary

1001000 1000101 1001100 1001100 1001111

Sort their files from largest to smallest 32kb 15gb 2mb 1.2gb 450b 900kb

15 GB 1.2 GB 2 MB 900 KB 32 KB 450 B

Convert DFF (hexadecimal) to decimal

3583

If you used 0,1,2 for each place and had three different places (i.e. 000, 012, 022, etc) how many how many different combinations would there be?

3^3= 27

Approximately how much bigger (how many more bytes) is a megabyte than a kilobyte?

A. 1,000 times bigger

8 bits is enough to represent 256 different numbers. How many total bits do you need to represent 512 (twice as many) numbers? A. 9 bits B. 10 bits C. 16 bits D. 17 bits

A. 9 bits

A middle school is trying to open a high school next year, doubling the number of students. The school keeps a database in which each students unique ID number is stored as an 8 bit number called student ID. Before the arrival of the new students almost every 8 bit number has already been assigned to a student. Of the options provided below, which is the smallest change to the way student ID is represented necessary to ensure each incoming student receives a unique ID?

A. Add a bit to Student ID to double the number of IDs that the database can represent.

DNS stands for

A. Domain Name System

An artist makes an RGB raster image in which each pixel color is encoded with 12-bits --- 4 bits each for red, green and blue. Which of the following correctly shows the hexadecimal value for Red as a 12-bit representation.

A. F00

which lines should be removed so the Program will work as intended?

A. Lines 3 and 4

A raw digital sound file samples a sound wave at some interval and measures the height of the wave at each point. Thus, raw sound is recorded as a list of numbers. In very broad terms the MP3 audio compression algorithm identifies frequencies and volume levels - low and high - that are outside the range of human hearing and removes the data representing these frequencies from the original. This technique results in a smaller audio file that sounds exactly the same to the human ear. This technique is an example of what type of compression?

A. Lossy compresion

Which of the following statements best describes the proprieties of public key encryption?

A. Public key encryption is an encryption method which relies on separate keys for encrypting and decrypting information

A device on a network that transfers packets toward their destination

A. Router

What advice will help her the most in creating high quality posters?

A. She should save photos with a lossless compression algorithm, to ensure that the posters are of highest quality.

Hank types this URL in his browsers address bar whcih of the protocols are used by the browser in fetching and loading the webpage?

A. TCP D. IP E. HTTP

Why is the CPU important?

A. Without a CPU the computer cant process the data that comes from the keyboard

Simplifying complexity in computer science is called

A. absrtaction

What can her computer do with that memory amount?

A. her computer can remember 16GB worth of instructions and data at any time, shared by all the open applications

A keyboard is an example of an ______ device input

A. input

_____ encryption is a method of encryption involving one key for both encryption and decryption

A. symmetric

Logic gates implement Boolean functions performing logical operations on one or more inputs and outputting a single binary value Which table correctly describes the Boolean functions implemented by each gate?

B. And -outputs 1 is both inputs are 1 OR- outputs 1 if at least one input is 1 NOT- outputs 1 if input is 0, and 0 if input is 1

Consider the following binary numbers: 01010 010000 1110 which of the following lists the numbers from least to greatest?

B. 01010 1110 010000

What is the 4-bit binary number for the decimal number Ten (10)?

B. 1010

Which of the following could be an IPv4 address?

B. 23.125.153.16

How many total bits are in an IPv4 address?

B. 32

ASCI is a character encoding scheme that uses a numeric value to represent each character. For example, the uppercase letter 'C' is represented by the decimal base 10 value 71. A partial list of characters and their corresponding ASCI values are shown in the table below.ASCI characters can also be represented bby binary numbers. According to ASCII character encoding, which of the following represents the binary number 0100 0010?

B. ASCII character B

Public Key encryption is considered to be ______ encryption

B. Asymmetric

Bett sends an instant message to her friend Meille over the internet. Their computers use the TCP/IP protocols to communicate. Whats the best description of how Bett's computer sends the message?

B. Betts computer splits the message into packets. It does a three way handshake with Mielles computer to establish the connection, then sends each packet to Mielles home router. If her computer detects packet loss, it resends the missing packets.

What two statements are true about parameters?

B. Functions with parameters can be used to prevent the creation of duplicated code. C. Parameters help generalize the solution of a specific problem.

What is the best explanation for why digital data is represented in computers in binary?

B. Its easier, cheaper, and more reliable to build machines and devices that only have to distinguish between two states

The time it takes to communicate between to nodes on a network

B. Latency

A compression scheme for long strings of bits called run-length encoding is described as follows: Rather than record each 0 and 1 individually, instead record "runs" of bits by storing the number of consecutive 1s and 0s that appear. Since it's binary, any run of 0s must be followed by a run of 1s (even if the run is only 1-bit long) and vice versa. Thus, you can store a list of small numbers that represents the alternating runs of 0s and 1s. Here is an example:

B. Lossless compression

Why are parameters useful when programming? A. Parameters determine the number of times the function will run. B. Parameters allow for more flexible, generalized behaviors in functions. C. Parameters are useful for teams of programmers because they help define the boundaries of the problem they are trying to solve. D. Parameters change the order of operations within a function.

B. Parameters allow for more flexible generalized behaviors in functions

A set of rules or procedures for transmitting data among electronic devices

B. Protocol

An apple mac computer includes a status with various indicators. which of the indicators could represent a single bit of information?

B. The source of the power (battery/ adapter) E. The Bluetooth status (disconnected/connected)

What does this icon look like?

B. a frowning face

choose the two correct definitions

B. bandwicth a measure of a bit rate- the amount of data (measured in bits) that can be sent in a fixed amount of time C. Latency, the time elapsed between the transmission and the receipt of a request

What is a function parameter?

B: a way to give input to a function that controls how the function runs

Which of the following could be an IPv6 address?

C. 2001:D238:0000:128:A178:FFFF: 2B6E

NSFnet was an early internet connecting the computer science departments of universities. In 1986, NSFNET connected 6 departments across the US: In this network, how many routes are between San Diego and Cornell?

C. 4 routes

Choose the answer that is NOT a feature if Public Key Cryptography

C. A Public Key database ensures 3rd party accountability of security

The number of bits that are transmitted each second is known as

C. Bitrate

Which of the following takes a human word URL and associates it with an IP address?

C. DNS

Which of the following uses TLS (Transport Layer Security) to keep information secure?

C. HTTPS

The image below shows an encoding for a black and white pixel image. The first two bytes of the data (circled in red) are used to encode the width and height of the image. What is the best term for this type of "data about the data"?

C. Metadata

When programmers work together, what is an example of how abstraction in programming can promote collaboration? A. Team members can rely on one another to explain their code. B. Programmers can write functions without needing to know what they do or how they should work. C. Programmers can use functions created by their partners, relying on the functionality without needing to know the specific details of how the function is implemented. D. In order for programmers to work together, they must work in the same room. E. Abstraction allows programmers to brainstorm more creative solutions to problems.

C. Programmers can use functions created by their partners, relying on the functionality without needing to know the specific details of how the function is implemented.

DevFest is a conference that wants to make sure it has a reliable connection to the internet. The conference partners with two internet providers, Comcast and Sonic, just in case one of them goes down. The ISP routers then connect to the rest of the internet. Which router has to stay available for DevFest to have a working connection to the internet?

C. Router A

The University of California at Davis has many IP addresses that can assign to its campus computers. One IP address is 169.237.121.44 Which explanation best describes the hierarchical nature of that address.

C. The first part of the address (169.237) identifies the network (UC Davis) and the second part (121.44) identifies the campus computer.

Which is the primary function of the CPU?

C. To process the instructions from a computer program

Taylor switched WiFi networks frim an AT&T network to a Verizon network. He noticed his IP address changed. Whats the best explanation for the change?

C. Verizon has a different set of IP addresses to allocate than AT&T, so Verizon had to give Taylor's computer a different IP address than the AT&T address

Under which of the following conditions is it most beneficial to use a heuristic approach to solve a problem?

C. When the problem cannot be solved in a reasonable time and an approximate solution is acceptable

What is the minimum number of bits you would need to encode the 26 letters of the alphabet plus a space--a total of 27 characters?

C. five bits

which of the following is not true about functions in programming

C. functions cannot make calls to other functions within the same program

The "computer" is a high level abstraction, and a computer can be implemented using other lower-level abstractions. Sort these from highest to lowest. computer binary numbers logic circuits logic gates

Computer Logic circuit Logic gate Binary numbers

Which of the following is the top level domain for www.example.com?

D. .com

How many total bits are in an IPv6 address?

D. 128

Two students have developed a protocol in which they send 4-bit messages to each other. They decide to modify their protocol to start sending 8-bit messages instead. How many more values can be represented in an 8-bit message than a 4-bit message?

D. 2^4=16 times as many values.

The language in which web pages are displayed in a web browser?

D. HTML

What protocol is used to send a GET request from a client computer to a website server asking for its webpage?

D. HTTP

Harper clicks one of her bookmarks to visit her favorite site "https://worldarchery.org/ she watches the website load Which of these describes how the website loaded?

D. Harper's browser sent an HTTP request to the web server that hosts "worldarchery.org/ The web server sent back an HTTP response with the HTML for the webpage.

Each IP packet contains a sequence number. What is the primary purpose of the sequence number?

D. It helps the receiving computer reassemble the packets

1000 bytes make up a

D. Kilobyte

Select the answer that lists the units of bytes in ascending order (from smallest to largest)

D. Kilobyte, gigabyte, terabyte

Whats a good explanation of the benefits and drawbacks to lossy compression algorithms?

D. Lossy compression algorithms reduce the size, but the compression is irreversible so you need to store the original images if you ever want to display the photos at a higher quality

Number systems with different bases such as binary (base-2) and decimal (base-10) are all used to view and represent digital data. Whch of the following is NOT true about representing digital data?

D. Some large numbers cannot be represented in binary and can only be represented in decimal.

TCP/IP are protocols that route data around the internet What are they responsible for?

D. TCP is responsible for reliable transmission of packets. IP is responsible for routing of packets from source to destination across the internet.

Which of these is the best description of the domain name system (DNS)?

D. The domain name system associates domain names with IP addresses, like "www.youtube.com" with 208.65.153.251

Which of the following is a true statement about data compression?

D. There are trade-offs involved in choosing a compression technique for storing and transmitting data.

A programmer is writing a system that is intended to be able to store large amounts of personal data. as the programmer develops the data system, which of the follwing is LEAST likely to impact the programmers choice in designing the structure of the system?

D. the frequency of a particular item occurring in a data set.

Which one pf the following statements about functions is true

E. Two functions in an single program can have different names but contain identical code

Using the ASCII table, what does 01100000 01001111 01010100 spell? (Convert the binary to decimal first)

HOT

How does HTTPS differ from HTTP and how can you tell if the website you are looking for uses HTTPS?

HTTPS has a layer of security. URL will start with https and often show a lock.

Explain why we have to progress from IPv4 to IPv6.

Not enough addresses in IPv4 to cover all devices

Small Groups of data that are transmitted on the internet

Packets

What protocol is in charge of making sure that packets are sent/received and put in the correct order?

TCP/IP

What is the most likely outcome of runnng the code at right

The program will run without error but not draw anything

Explain why Vigenere's cipher is much harder to crack than Random substitution

With Vigeneres' cipher, you can't use frequency analysis while you can with random substitution.

Which of the following will call the function drawStar?

drawStar();

Drawing a circle of any size at any point on the screen

function

Drawing 100 tiny dots in a line

loop

What is a protocol?

set of rules

What is a major disadvantage of using wifi

short range