Data Transmission Flashcards
How is data transmitted?
Data is broken down into packets through a method called packet switching, it is then transmitted over a network of routers and when each packet reaches its destination the data is reassembled
What is the structure of a packet?
A packet consist of a header(this holds things like the ip address of the sender and receiver and the sequence number of the packet for reassembly upon its destination), the payload(this is the actual data) and the trailer(this holds the method of identifying the end of the packet and some form of error checking)
What is packet switching?
Packet switching is a method of data transmission in which a message is broken up into a number of packets. Each packet can then be send independently from start point to end point.
What is a hop number?
A hop number is a number given to the header each packet , this number reduces by 1 every time it leaves a router. If the hop number reaches 0 and it hasn’t reached its destination, it is deleted when it reaches the next router and it is flagged by the receiving computer and a request to re-send the packet is made.
What is meant by bandwidth?
Bandwidth is the amount of data that can be carried at one time
What is serial transmission?
Serial transmission is a method of transmission where bits are sent one signal at a time over a single wire. This allows for very high data transfer rates
What is meant by parallel transmission?
Parallel transmission is a method of transmission where bits are sent simultaneously over a number of parallel wires.
What are integrated circuits?
Integrated circuits is made of a semiconductor which holds many tiny resistors, transistors and resistors sending data in parallel
What is simplex transmission?
Simplex transmission is where data travels in one direction only
What is half duplex transmission?
Half-duplex transmission is where data can travel in both directions along a single cable but not simultaneously
What is full duplex transmission?
Full duplex transmission is where data can travel in both directions simultaneously using two cables
What is meant by the bit rate?
What is meant by the baud rate?
The bit rate is the speed of data in bits per second
The baud rate is the rate at which the signal changes
How is the bit rate of a channel calculated?
Baud rate X number of bits per signal
What is plain text?
Plain text is the message before it has been encrypted
What is cypher text?
Cypher text is the message after it has been encrypted
What is encryption?
Encryption works by scrambling a message into a secret code that can only be deciphered using a unique digital key
What is symmetric encryption?
Symmetric encryption is where both the sender and receiver use the same encryption key to encrypt and decrypt the message
What is asymmetric encryption?
Asymmetric encryption is where the sender and receiver have a public key which can be used to encrypt the message but only the person with the private key can decrypt the message
What is malware?
Malware refers to any software written with malicious intent
Name 3 types of malware
Spyware
Viruses
Ransomware
What is a denial of service attack (Ddos)
A denial of service attack is a cyber attack in which a server is flooded with requests in the attempt of overloading it or making it crash
What does anti-virus software do?
Detects viruses
Deletes or quarantines infected files
