1.
An error correcting code has the following code words:
00000000, 00001111, 01010101, 10101010, 11110000.
What is the maximum number of bit errors that can be corrected ?
Correct Answer
D. 3
Explanation
The maximum number of bit errors that can be corrected is 3 because the given code words have a Hamming distance of 4. Hamming distance is the number of bit positions in which two code words differ. By comparing each code word to the others, we can see that the minimum Hamming distance is 4, which means that the code can correct up to 3 bit errors.
2.
​​​​​Which transmission media has the highest transmission speed in a network?
Correct Answer
C. Optical fiber
Explanation
Optical fiber has the highest transmission speed in a network compared to other transmission media such as coaxial cable, twisted pair cable, and electrical cable. Optical fiber uses light signals to transmit data, allowing for faster transmission speeds and higher bandwidth capabilities. It has low signal loss, is less susceptible to electromagnetic interference, and can transmit data over longer distances without degradation. These factors make optical fiber the preferred choice for high-speed and long-distance communication networks.
3.
Wireless transmission can be done via
Correct Answer
D. All of the mentioned
Explanation
Wireless transmission can be done through various methods such as radio waves, microwaves, and infrared. All of these mentioned options are valid means of wireless transmission. Radio waves are commonly used for long-distance communication, microwaves are used for satellite communication and short-range wireless devices, while infrared is used for short-range communication between devices like remote controls. Therefore, all of the mentioned options are correct for wireless transmission.
4.
When 2 or more bits in a data unit has been changed during the transmission, the error is called
Correct Answer
B. Burst error
Explanation
When 2 or more bits in a data unit have been changed during the transmission, the error is called a burst error. This type of error occurs when a cluster of errors happens consecutively, affecting multiple bits within a short period. It is different from random errors, which occur sporadically and affect individual bits. Inverted error is not a recognized term in the context of data transmission errors.
5.
CRC stands for
Correct Answer
A. Cyclic redundancy check
Explanation
CRC stands for cyclic redundancy check. It is an error-detecting code that is commonly used in digital networks and storage devices. It is used to detect errors in data transmission or storage by generating a checksum based on the data and comparing it with the received or stored checksum. If the checksums do not match, it indicates that an error has occurred. The cyclic redundancy check is an important tool in ensuring data integrity and reliability in various applications.
6.
Coaxial cable consists of _______ concentric copper conductors.
Correct Answer
B. 2
Explanation
Coaxial cable consists of two concentric copper conductors.
7.
Carrier is
Correct Answer
B. A continuous frequency capable of being modulated or impressed with a second signal
Explanation
The correct answer is "a continuous frequency capable of being modulated or impressed with a second signal." This is because a carrier is a signal that is used to carry information. It is a continuous frequency that can be modified or combined with another signal to transmit data or communicate. This definition aligns with the given answer option.
8.
In CRC there is no error if the remainder at the receiver is ____
Correct Answer
C. Zero
Explanation
In CRC (Cyclic Redundancy Check), the remainder at the receiver being zero indicates that there is no error in the transmitted data. This is because the receiver performs the same CRC calculation as the sender using the received data and the same polynomial. If the remainder at the receiver is zero, it means that the received data has been successfully verified and no errors were detected during transmission.
9.
Find even parity bit for 1001011
Correct Answer
A. 0
Explanation
The given question asks to find the even parity bit for the binary number 1001011. Parity bit is used to detect errors in data transmission. In even parity, the number of 1s in the data should be even. In the given binary number, there are 4 1s, which is an even number. Therefore, the even parity bit for this binary number is 0.
10.
If value of checksum is 0, then message is
Correct Answer
A. Accepted
Explanation
If the value of the checksum is 0, it means that the calculated checksum of the message matches the expected checksum. This indicates that there are no errors or corruption in the message during transmission. Therefore, the message is accepted as valid.
11.
The checksum of 1111 and 1111 is _________.
Correct Answer
A. 0000
Explanation
When calculating the checksum, the sum of the two numbers is taken. In this case, 1111 + 1111 equals 2222. However, since we are working with a 4-bit binary system, the checksum is obtained by taking the remainder of the sum divided by 16. In this case, 2222 divided by 16 equals 138 with a remainder of 14. Therefore, the checksum is 0000.
12.
The ________ between two words is the number of differences between corresponding bits.
Correct Answer
C. Hamming distance
Explanation
The Hamming distance between two words refers to the number of differences between corresponding bits. It is a measure of the similarity or dissimilarity between two binary strings. The Hamming distance is commonly used in computer science and information theory to detect and correct errors in data transmission.