Acronyms and Concepts

Question 1

What is CBC

Answer 1

Cipher Block Chaining - used to eliminate the need for a ‘random key’ when encrypting using Block Ciphers.

Question 2

What is RSA

Answer 2

Asymmetric (Public-Private key) Encryption Algorithm

Question 3

What is KDC

Answer 3

Key Distribution Centre

Question 4

What is PGP

Answer 4

Pretty Good Privacy: a combination of both symmetric and asymmetric cryptography.
Key idea: to use public key encryption to distribute symmetric keys.

Question 5

What is MAC (Encryption)

Answer 5

Message Authentication Code: A hash of the message + symmetric key that you send to the receiver.

Question 6

What is Digital Signiture

Answer 6

Encrypt the hash with your private key instead and send along with the original message.

Question 7

What is CA (Encryption)

Answer 7

Certification Authority.

Question 8

What is DSL

Answer 8

Digital Subscriber Line

Question 9

What is HFC

Answer 9

Hybrid Fiber Coaxial. Refers to neighbourhood line to the cable headend being made up of Fiber. Pretty much the BUS is made up of Fiber.

Question 10

What is TP

Answer 10

Twister Pair. Makes use of two insulated copper wires, which are twisted to reduce interference.

Question 11

What is FDM

Answer 11

Frequency Division Multiplexing.

Key idea: divide the channel based on frequency and total number of users.

Question 12

What is TDM

Answer 12

Time Division Multiplexing.

Key idea: divide the channel based on time and total number of users.

Question 13

Explain Packet Switching

Answer 13

Purpose: Allow more users to use a network at once

Question 14

IXP

Answer 14

Internet Exchange Point. Where all ISP’s can connect, so that they may exchange data (Level 1 ISPS).

Question 15

CDN

Answer 15

Content Distribution Networks.

Question 16

What is POP

Answer 16

Point of Presence. The two end points of links between ISPs.

Question 17

AIMD (Congestion Control)

Answer 17

Additive Increase Multiplicative Decrease.
Key idea: to make full use of bandwidth without over congesting the network, sender should continually increase the transmission rate (window size), until the first packet is dropped - at which point the packet size should be halved and the process should be repeated.

Question 18

HOL (Blocking)

Answer 18

Head of the Line.
The packet at the front of the buffer prevents previous packets from going to their respective output port, even though they’re destination port is not being used.

Question 19

MTU

Answer 19

Maximum Packet Transfer Size

Question 20

IP Fragmentation

Answer 20

Dividing packets too large for a network into smaller packets instead.

Question 21

CIDR

Answer 21

Classless Inter Domain Routing

Question 22

DHCP

Answer 22

Dynamic Host Configuration Protocol

Question 23

NAT

Answer 23

Network Address Translation

Question 24

RIP

Answer 24

Routing Information Protocol.

Based off of distance vector algorithm.

Question 25

OPSF

Answer 25

Open Shortest Path First.

Based off Dijkstra’s algorithm.

Question 26

What is BGP

Answer 26

Border Gateway Protocol

Question 27

What is CRC

Answer 27

Cyclic Redundancy Check

Question 28

CDMA

Answer 28

Code division multiple access.

Key idea: splitting the channel based on codes allocated to devices.

Question 29

What is CSMA

Answer 29

Carrier Sense Multiple Access.

Question 30

What is CSMA/CD

Answer 30

Collision Detection (Wired)

Question 31

What is CSMA/CA

Answer 31

Collision Avoidance (Wireless)

Question 32

What is RTS

Answer 32

Request to Send.

Question 33

What is CTS

Answer 33

Clear to Send