Computer networks

Question 1

LAN

Answer 1

Local Area Network

Question 2

MAN

Answer 2

Metropolitan Area Network

Question 3

WAN

Answer 3

Wide Area Network

Question 4

PAN

Answer 4

Personal Area Network

Question 5

client-server model

Answer 5

Distributed application structure that partitions workloads and tasks between the providers of a resource or service (server) and service requesters (client).

Question 6

peer to peer (P2P)

Answer 6

P2P computing or networking is a distributed application architecture that partitions tasks and workloads between equipotent participants (peers). E.g. torrent.

Question 7

circuit switching

Answer 7

A method of implementing a telecommunication network in which two network nodes establish a dedicated communications channel (circuit).

Question 8

packet-switching

Answer 8

A type of network in which relatively small units of data (packets) are routed through a network based on the destination address contained within each packet. (connectionless communication)

Question 9

ISO OSI layers

Answer 9

application,
presentation,
session,
transport,
network,
datalink,
physical

Question 10

application

Answer 10

supporting network applications: ftp, smtp, http

Question 11

transport

Answer 11

-reliable end-to-end communication
-creates the abstraction of an error-controlled, dlow controlled and multiplexed end-to-end link
TCP: error-control, flow control, multiplexing
UDP: only multiplexing

Question 12

network

Answer 12

-logically concatenates a set of links to form the
abstraction of an end-to-end link
-routing of datagrams from source to destination: ip, routing protocols
-provide unique network-wide addresses
-both in end-systems and intermediate systems

Question 13

link

Answer 13

-the first layer of software
-usually in a bundle with the physical layer in the hardware
-data transfer between neighbouring network elements: ppp, ethernet

Question 14

Internet

Answer 14

-network layer is provided by the Internet Protocol (IP)
-found in all end-systems and intermediate systems
-provides abstraction of end-to-end link
-packet-fowarding, routing, scheduling
-unique IP-address

Question 15

error control

Answer 15

GOAL:
-message reaches its destination despite packet loss, duplication and corruption
ACTION:
-retransmits lost packets
-detect, discard and retransmit corrupted packets
-detect and discard duplicated packets

Question 16

flow control

Answer 16

Match transmission rate to the rate sustainable on the path to destination and at the destination.

Question 17

twisted pair cable

Answer 17

Twisted pair cabling is a type of wiring used for communications in which two conductors of a single circuit are twisted together for the purposes of improving electromagnetic compatibility.
-two conductors, each with plastic insulation
-two types: shielded (STP), unshielded (UTP)

Question 18

RJ

Answer 18

A registered jack (RJ) is a standardized telecommunication network interface for connecting voice and data equipment to a service provided by a local exchange carrier or long distance carrier.
-the most common UTP connector
-RJ45 male and RJ45 female

Question 19

Coaxial cable

Answer 19

Coaxial cable is a type of electrical cable consisting of an inner conductor surronded by dielectric insulator and a concentric conducting shield.
-many have an outer protective plastic jacket/sheath

Question 20

BNC connector

Answer 20

Bayone-Neill-Concelman connector
-the most common type of connector for coaxial cables
-types: BNC connector, BNC T connector, BNC terminator
-applications: TV cables, traditional LANs

Question 21

optical fibre

Answer 21

Optical fibre is a transparent fibre made of silica. It’s mostly used for fibre-optic communications because they allow electromagnetic waves to travel long distances with small loss and interference.
-a dielectric waveguide that trasmits light along its axis due to internal refraction
parts:
-glass or plastic core
-cladding
-plastic buffer
-coating
-outer jacket

Question 22

multimode fibre

Answer 22

-designed for small distances of transmission: LAN-systems, video surveillance

Question 23

single mode fibre

Answer 23

-designed for larger distances of transmission: long distance telephony, multichannel television broadcast systems

Question 24

unguided media

Answer 24

Unguided media (wireless communication) is the transport of electromagnetic waves without using a soild physical conductor.
The section of the electromagnetic spectrum called the radio communication is divided into 8 ranges (bands).

Question 25

ground propagation

Answer 25

Radio waves travel through the lowest portion of the atmosphere. These emitted waves emanate in all directions from the transmitting antenna following the curvature of the earth.

Question 26

sky propagation

Answer 26

Higher-frequency radio waves radiate upwards into the ionosphere and are reflected back to Earth. This type of transmission allows higher frequencies with lower power output.

Question 27

line-of-sight propagation

Answer 27

Very high-frequency signals are transmitted in a straight line from antenna to antenna.

Question 28

Consumer IR

Answer 28

CIR refers to a wide variety of devices employing the infrared electromagnetic spectrum for wireless communication.

Question 29

IrDA

Answer 29

Infrared Data Association; an industry-driven founded in 1993 by 50 companies. IrDA provides specifications for a complete set of protocols for wireless infrared communications.

Question 30

star topology

Answer 30

-central hub through which all traffic flows
-the hub is a central point of failure
-used in all LAN networks
-simple to implement, easy to monitor all connected devices

Question 31

bus topology

Answer 31

-all devices in the network are connected by a single cable
-any break in the cable renders the system inoperable

Question 32

ring topology

Answer 32

-normally associated with Token Rings and FDDI environments
-can use dual counter-rotating rings that tolerate a single break
-expensive to implement
-the access protocols are more complex, the devices more intelligent