AP CSP Unit 1 Assessment Review

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

• At one of the lowest levels of abstraction, all digital data can be represented in binary using only combinations of the digits zero and one

• The same value (number) can have a different representation depending on the number system used to represent it

• Groups of bits can be used to represent abstractions, including but not limited to numbers and characters

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

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

• The binary number system is the only system flexible enough to allow for representing data other than numbers

• It's easier, cheaper, and more reliable to build machines and devices that only have to distinguish between binary states

• It typically takes fewer digits to represent a number in binary when compared to other number systems (for example, the decimal number system)

• It's impossible to build a computing machine that uses anything but binary to represent numbers

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

• 0010

• 1010

• 0110

• 0101

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?

• 2 bits

• 3 bits

• 5 bits

• 6 bits

A middle school is expanding to open a high school next year, doubling the total number of students. Student's unique ID number is currently stored as an 8 bit number. Which of the options below is the smallest change to the way student ID is represented to ensure each incoming student receives a unique ID?

• Add a bit to studentID to double the number of IDs that the database can represent.

• Double the number of bits in studentID to double the number of IDs that the database can represent

• Keep using an 8-bit number for studentID but reserve the first bit to indicate middle school or high school

• Remove a bit from studentID to make room for incoming students

8 bits is enough to represent 256 different numbers. How many total bits do you need to represent 512 (twice as many) numbers?

• 9 bits

• 10 bits

• 16 bits

• 17 bits

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?

• 2 to the 1st power = 2 times as many values

• 2 to the 2nd power = 4 times as many values

• 2 to the 3rd power = 8 times as many values

• 2 to the 4th power = 16 times as many values

Which statement below is true about routers and routing on the Internet?

• Routers are hierarchical and the "root" router is responsible for communicating to sub-routers the best paths for them to route internet traffic.

• Packets travelling to the same destination always take the same path between routers.

• A packet traveling between two computers on the Internet may be rerouted many times along the way or even lost or "dropped".

• Protocols ensure that a single path between two computers is established before sending packets over it.

The various protocols in use on the internet are said to operate in layers in which the protocol(s) at each layer solve one problem related to networked communication, and higher layers are built on top of, and rely on, the lower layers to do their jobs. From the choices below, choose the answer that correctly describes which internet protocol relies on the other.

• TCP/IP relies on HTTP

• TCP/IP relies on DNS

• DNS relies on TCP/IP

• Physical Internet relies on TCP/IP

Which of the following BEST describes how protocols on the Internet (e.g. IP, TCP, HTTP) make use of abstraction to accomplish their respective purposes?

• High level protocols take into account specific implementation details of lower level protocols to ensure they are compatible.

• Low level protocols can provide functionality to high level protocols without revealing the details of how this is accomplished.

• Low level protocols are written in binary while high level protocols are written in hexadecimal.

• High level protocols can take on the role of a low level protocol in the event of failure in the system.