(Finals) Data and Digital Communication Mocktest BSIT - 505

61問 • 3ヶ月前

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It is always present to some degree in transmission media and electronic devices and is dependent on the temperature of the medium. In this noise, when the temperature increases, the level of noise increases because of the increased activity of the electrons in the electronic device.

White noise (Thermal noise or Gaussian noise)

is a noncontinuous noise and one of the most difficult errors to detect because it can occur randomly. Typically, the noise is an analog burst of energy. If the impuls e spike interferes with an analog signal, removing it without affecting the original signal can be difficult.

Impulse noise (Noise spike)

It is an unwanted coupling between two (2) different signal paths. This unwanted coupling can be electrical, as might occur between two (2) sets of twisted pair wire (as in a phone line), or it can be electromagnetic (as when unwanted signals are picked up by microwave antennas)

Crosstalk

It is the reflective feedback of a transmitted signal as the signal moves through a medium. It is usually a signal bouncing back from the end of a cable and creating it.

Echo

It is the result of small timing irregularities that become magnified during the transmission of digital signals as the signals are passed from one device to another. To put it another way, when a digital signal is being transmitted, the rises and falls of the signal can start to shift or become blurry and, thus, produce it.

Jitter

It is the continuous loss of a signal's strength as it travels through a medium. It is not necessarily a form of error but can indirectly lead to an increase in errors affecting the transmitted signal.

Attenuation

What type of error is this? It indicates that only one (1) bit of a given data unit (such as a byte, character, or packet) is changed from 1 to 0 or from 0 to 1

single-bit error

What type of error is this? This indicates that two (2) or more bits in the data unit have changed from 1 to 0 or from 0 to 1. The duration of the noise signal is normally longer than the duration of 1 bit, which means that when noise affects data, it affects a set of bits.

burst error

It is the central concept in detecting or correcting errors.

Redundancy

It can be performed in the data link layer. When a device creates a frame of data at the data link layer, it inserts some type of error detection code.

Error Detection

It is a simple method of error detection is by adding redundant bits called parity bits to each character.

Parity Check (Vertical Redundancy Check)

Which sentence is NOT TRUE about Parity Check (Vertical Redundancy Check)?

Specifically, each row of the array is a data block that is to be transmitted

In this type of checking, blocks of data are organized as a two-dimensional array. This method increases the likelihood of detecting burst errors

Two-Dimensional Parity (Longitudinal Redundancy Check

Which statement is NOT TRUE about Two-Dimensional Parity (Longitudinal Redundancy Check?

It comes in two (2) basic forms: even parity and odd parity. The basic concept of parity checking is that a bit is added to a string of bits to create either even parity or odd parity.

It is a sequence of numbers and letters used to check data for errors. This sum is then added to the end of the message, and the message is transmitted to the receiving end

Arithmetic Checksum

Which statement is NOT TRUE about Arithmetic Checksum?

Review the XOR function and Binary Division.

This method treats the packet of data to be transmitted (the message) as a large polynomial,which adds 8 to 32 check bits to large data packets and yields an error-detection capability,approaching 100 percent.

Cyclic Redundancy Checksum

Which statement is NOT TRUE about Cyclic Redundancy Checksum?

It has two (2) sides: sender’s side (checksum creation) and receiver’s side (checksum validation)

Which statement is NOT TRUE about Error Correction?

A simple method of error detection is by adding redundant bits called parity bits to each character.

It is used to deal with errors that occur when the stop-and-wait flow control protocol is used.

Stop-and-Wait ARQ

Which is NOT TRUE about how errors can occur?

the source was not found

It deals with errors that occur when the sliding window protocol is used.

Go-Back-N ARQ

Under this scheme, only the frame in error is retransmitted. The drawback is that the receiver must provide enough buffer to store the frames that were transmitted after the erroneous frame until the frame has been retransmitted.

Selective Repeat ARQ

It is the art of ensuring that data is kept private and accessed only by the intended recipient. It does not only apply to the storage of information, but it also applies to the transmission of information.

Confidentiality

Which statement is NOT TRUE ABOUT Confidentiality?

is the art of ensuring that data is transmitted from source to destination without alteration.

is the art of ensuring that data is transmitted from source to destination without alteration. It means that changes need to be done only by authorized entities and through authorized mechanisms. It is accomplished with the use of a digital signature, which is a way to know that an electronic document is legit and authentic.

Integrity

Which statement is NOT TRUE about Integrity?

It is the information created and stored by an organization that needs to be available to authorized entities

It is the information created and stored by an organization that needs to be available to authorized entities. Information is useless if it is not available. Information needs to be constantly changed, which means it must be accessible to authorized entities.

Availability

It is the process of verifying that the user is exactly who he claims to be.

Authentication

It is usually done through the use of passwords or user IDS.

Single-factor authentication

It is a two-step verification that provides an extra layer of security beyond user ID and password, usually with a software code generator or a hardware-based login key.

Two-factor authentication

Which statement is NOT TRUE about Authentication?

It is accomplished through encryption.

Which Statements are TRUE about Network Attacks?

It is an intrusion on network infrastructure., The attacker first analyzes the environment and collects information in order to exploit the existing open ports or vulnerabilities., An attack can be performed either from outside of the organization by an unauthorized entity or from within the company by an “insider” that already has some access to the network.

In Attack threatening Confidentiality, It refers to unauthorized access to or interception of data.

Snooping

In Attack threatening Confidentiality, Although encipherment of data may make it unintelligible for the interceptor, she can obtain some other types of information by monitoring online traffic.

Traffic Analysis

In Attacks Threatening Integrity, After intercepting or accessing information, the attacker modifies the information to make it beneficial to herself.

Modification

In Attacks Threatening Integrity, happens when the attacker impersonates somebody else.

Masquerading

In Attacks Threatening Integrity, The attacker obtains a copy of a message sent by a user and later tries to replay it.

Replaying

In Attacks Threatening Integrity, This type of attack is different from others because it is performed by one of the two parties in the communication: the sender or the receiver.

Repudiation

In Attacks Threatening Availability, it may slow down or totally interrupt the service of a system.

Denial of Service (DoS)

It is a process of capturing the data packets traveling in the network. It is used by IT professionals to analyze and monitor the traffic to find such things as unexpected suspicious traffic.

Network sniffing (packet sniffing)

It is a process by which an intruder masquerades as a trusted user in order to gain unauthorized access to a secure environment.

Spoofing

It is a process of creating IP packets with forged source IP address to impersonate a legitimate system. This kind of spoofing is often used in denial-of-service (DoS) attacks.

IP address spoofing

It is a process of sending fake ARP messages in the network. The purpose of this type of spoofing is to associate the MAC address with the IP address of another legitimate host, causing traffic redirection to the attacker’s system

ARP spoofing

It is an attack where the wrong data is inserted into the DNS server cache, causing the DNS server to divert the traffic by returning wrong IP addresses as the results for client queries.

DNS spoofing

It is an attack that involves placing a software agent between the client and server ends before or during a communication session.

Man-in-the-middle (MITM) attack

It is an attack that is aimed at preventing unauthorized users from accessing services on the network.

Denial-of-Service (DoS)

It is a program that installs malicious software while under the guise of doing something else.

Trojan horse

It refers to the exploitation of a valid computer to gain unauthorized access to information or services in a computer system. In particular, it is used to refer to the theft of a magic cookie used to authenticate a user to a remote server.

Session hijacking

It is an attack in which the attacker attempts to fraudulently acquire sensitive information, such as usernames, passwords, and credit card details, by masquerading as a trustworthy entity in a communication session. It is typically carried out by e-mail or instant messaging and often directs users to give details on a website.

Phishing

It is a method of concealing information from a recognizable text into encrypted form

Encryption

Encryption transforms readable text, called plaintext (or cleartext), into an unintelligible form, called

Ciphertext

The purpose of this is to scramble a message so that it remains secure even if the ciphertext is transmitted over a nonsecure medium.

Encryption Algorithm

The process of recovering a plaintext from its ciphertext is called

Decryption

It is a system that encrypts and decrypts information

Cryptosystem

It the art of creating and using cryptosystems

Cryptography

It is the art of breaking encrypted messages (usually by intruders)

Cryptanalysis

It is the study of cryptography and cryptanalysis

Cryptology

Both encryption and decryption use this, in which in the cryptographic sense, is a long string of characters that permits a cryptosystem to encrypt or decrypt information in a distinct way.

key

The same key is used for encryption and decryption. Both the originator and the recipient of a message must know the key, which is either known to the recipient through some prior arrangement or communicated in parallel with the ciphertext.

Symmetric Cryptosystems

This uses one key (public-key) for encryption and another key (private-key) for decryption. Each user is assigned a pair of unique and mathematically related keys: a public key and a private key. The private key is a secret key that is available only to the owner, and the public key is published.

Public-Key Cryptosystems (or Asymmetric Cryptosystems)

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