Chapter 2.1 - Networking (AS + A2)

Question 1

test your knowledge from IGCSE CompSci with this question:

how do both MAC and IP addresses help identify devices connected to the internet?

(hint: each hardware device has its own MAC address)

Answer 1

• MAC addresses: allow each and every hardware device to be distinguishable from one another
• IP addresses: assigned to devices connecting to the internet as either static or dynamic identifiers

(more on this later on)

Question 2

compare the following types of networks with each other:

LANs, MANs, and WANs

(hint: the internet can be considered one big fat international WAN!)

Answer 2

1. LANs: restricted to smaller geographical areas like school campuses and offices thus not costing as much to set the relevant hardware up
2. MANs: less geographically restricted than standalone LANs but still limited to connecting different LANs within single-settlement areas
3. WANs: used when connecting LANs/computers that’re really far away from each other + usually set up via public comms networks (e.g. ARPAnet/the internet)

(NB: some people also use the term PANs to refer to home networks)

Question 3

list the potential pros and cons of doing the following:

networking computers

(hint: consider the potential file servers have)

Answer 3

• pros: device + data sharing, cheaper proprietary software licenses, centralized servers + backups, online communications + oversight
• cons: initial cabling/server setup expenses being potentially high, device breakdowns/malware + hacking potentially downing an entire network

(NB: preventional measures like firewalls can help against some of the breakdown-related cons)

Question 4

list some hard + soft infrastructure involved in the following:

setting networks up

(hint: try dividing your ideas into hardware, software, and services)

Answer 4

1. hardware involved: networking cards, Internet routers (wired + wireless), physical switches, copper/glass cabling
2. software involved: network ops + management software, software firewalls, security utilities
3. possible services: DSLs, satellite comms channels, wired + wireless protocols (eg. Ethernet/Wi-Fi), IPs

Question 5

compare the following network categories with each other:

public and private networks

(hint: the owners of each category are different)

Answer 5

• public nets: carrier company-owned + used by multiple entities with subnetworks possibly being under some form of security management
• private nets: single organization-owned + maintained with restricted-access intranet-level security management

Question 6

list some of the differences between a wired LAN and the following:

WLANs

(hint: there’s less hardware involved!)

Answer 6

1. they don’t use any wiring/cabling when connecting devices
2. they use multiple WAPs (wireless access points) to make up for the lack of hardware-based connections

Question 7

compare the following networking models with each other:

client-server and P2P

(hint: there’s some degree of decentralization in the latter)

Answer 7

• client-server: more centralized with multiple client workstations connected to a single server + more vulnerable to full-on breakdowns as a result (most suitable for monitoring-and-security purposes/centralized backups/larger userbases)
• P2P: less centralized so doesn’t completely fall off if one of the peers goes down + riskier for security and integrity purposes as a result (most suitable for smaller userbases/workstation-based apps)

(in P2P networks files can become outdated due to repeated duplication)

Question 8

compare the following client types with each other:

thick and thin clients

(hint: consider the magnitudes of server dependency)

Answer 8

• thick clients: less reliant on network connections so have some of their features enabled via locally-stored resources even when offline but can pose risks to data security + integrity with that
• thin clients: more reliant on network connections so don’t require lots of expensive hardware but break down more easily without a working network connection

Question 9

list the 4 main types of the following:

network topologies

(hint: some are centralized while others aren’t)

Answer 9

1. bus nets (single-cable P2P networks w/ terminators at both ends + the capacity for only one transmission at a time)
2. star nets (centralized networks w/ all nodes connected to a single hub/switch + a lower risk of data collisions occurring)
3. mesh nets (multi-cable P2P networks w/ the routing type giving nodes some router-like capabilities + the flooding type being more likely to get unnecessarily loaded due to the lack of any routing logic) like the internet
4. hybrid nets (networks that combine any of the above topologies together thus allowing for larger nets to be created + networking faults to be easily identified)

Question 10

list the three main types of the following:

cloud storage systems

(hint: some cloud storage environments mix systems together)

Answer 10

1. public cloud (distinguishes the client and storage provider from each other)
2. private cloud (works behind organizational firewalls w/ client-provider integration)
3. hybrid cloud (combines public and private cloud environments to allow more sensitive data to be stored behind organizational firewalls)

Question 11

list some pros and cons of using the following:

cloud storage

(hint: it’s accessed via an internet connection)

Answer 11

• pros: remotely accessible via an internet connection, no personal hardware needed, easier to request backup and recovery services
• cons: can be problematic on slower/shakier internet connections, can become expensive the larger the storage needs become, can result in data losses if the relevant provider goes bankrupt/the cloud server gets attacked

Question 12

compare the following wireless networking technologies with each other:

Wi-Fi and Bluetooth

(hint: the latter’s used for shorter distances)

Answer 12

• Wi-Fi: highly secure + wider-ranged (ie. accessible from any WAP/hotspot within a 100m range from a device) thus suiting it better for full-scale net ops
• Bluetooth: transmits data within a 79-frequency EM band with random spread-spectrum frequency hopping + encrypted WPANs thus suiting it better for situations involving 30-meter ranges where transmission rates aren’t as critical

(both of them use EM radiation though)

Question 13

try this question out:

how can wireless signals be transmitted over longer distances?

(hint: terrestrial methods are impossible due to the Earth’s curvature)

Answer 13

by satellites orbiting over the Earth + strengthening signals from antennae

(more on the use of satellites for wireless networking later~)

Question 14

list three different types of cables used for the following:

wired networking

(hint: you might be connected to a fiber optic-based network right now)

Answer 14

1. twisted-pair cables (cheap yet very prone to interference + slow data transmission rates - commonly seen in LANs w/ the unshielded type found in homes + the shielded type in commercial buildings)
2. coaxial cables (more expensive yet less prone to interference + 80 times more capable of simultaneously transmitting data than twisted-pair cables combined w/ anti-jamming - commonly seen in MANs + cable TV installations)
3. fiber optic cables (the least prone to interference w/ light pulses being used for data transmission instead of electricity + single-mode cables reflecting less than multi-mode ones due to having only one light source - commonly seen in longer-distance applications)

Question 15

compare the following with each other:

wired vs wireless networking

(hint: wireless networking uses EM waves)

Answer 15

• wired: less prone to interference + creating dead spots but requires immobile devices + can result in tripping hazards/electrical fires/etc.
• wireless: easier to expand due to the higher mobility of the devices involved but can be interfered with more easily given its lower security

(NB: some jurisdictions have regulations that restrict specific EM frequencies for different purposes)

Question 16

describe the purposes of the following networking devices:

switches, repeaters, bridges, routers, and modems

(hint: the first one’s involved in the receiving side of a transmission)

Answer 16

1. switches - transmit data packets to the intended recipient(s) only by working the MAC address(es) out as part of a star topology thus making them more secure than hubs
2. repeaters - boost longer-distance wireless networking signals to reduce dead spot numbers but have no more than one collision domain
3. bridges - interconnect multiple same-protocol LANs together in a way that reduces the unnecessary flood risk for larger networks
4. routers - help data packets reach their intended extranet destinations by converting them between protocols so they can join another network (e.g. the large internet WAN)
5. modems - allow digital data transmission over analog channels and vice versa by modulating that data with a public comms infrastructure connection

Question 17

list the typical contents of the following:

a network interface card (NIC)

Answer 17

• the device’s MAC address
• an antenna (for WNICs)

Question 18

list a few points about the following wired LAN protocol:

Ethernet

(hint: besides nodes there are two other components in the protocol)

Answer 18

1. it contains three main components (device nodes, medium paths, and frames containing addresses)
2. using it allows for conflicts if there are multiple connected devices sharing the exact same IP address + collisions if there are multiple data transmissions over the same channel

(more on detecting collisions up next)

Question 19

try to explain the steps of the following Ethernet-based protocol:

CSMA/CD (carrier-sense multiaccess with collision detection)

(hint: it involves simple physics)

Answer 19

1. one node stops with its voltage-changing frame transmissions after a collision gets detected and transmits jam signals instead
2. it then sends the data it was gonna send before again after waiting for a random time interval

Question 20

list the pros and cons of the following:

bit streaming

(hint: it’s done via data transmissions on the internet)

Answer 20

• pros: no need to download an entire file from a server that may waste disk space, allows for on-demand playback without any specialist hardware, can provide protection from piracy
• cons: impossible to do when the connection gets lost, may result in temporary pauses if there’s insufficient buffer capacity based on bandwidth, often tied up with security and copyright issues

(more on the types of bit streaming on the next card)

Question 21

compare the following types of bit streaming with each other:

on-demand and realtime

(hint: the latter’s often seen in Twitch/YT livestreams)

Answer 21

• on-demand bit streaming: involves digital file conversion into a bit streaming format so the encoded file can then be linked to on a web server and downloaded in contiguous bitstreams w/ the ability to pause/fast-forward/rewind
• realtime bit streaming: involves encoding camera-captured video signals into a digital media format so the stuff being captured can then be viewed w/o the ability to pause/fast-forward/rewind