2.1. Networks including the Internet (Continued) Flashcards
1
Q
Importance of high broadband speed / bit-rate
A
- User has to download and display bits at same time
- If media is of higher quality, then higher broadband
speed needed since each “frame” is of a larger size - Real-time needs faster broadband speeds as
compared to on-demand, since there are a greater
number of users simultaneously requesting same
data
2
Q
Cloud Computing
A
- Refers to the on-demand provision of computing
services through the internet - Services provided include
- Infrastructure: Storage capacity and higher
processing power - Platform: Software, testing & debugging resources
3
Q
Public cloud
A
- 3rd-party cloud service
provider grants access to
multiple parties, accessible
via a browser - Cloud service provider owns,
develops and manages the
public cloud through large
server farms
4
Q
Private cloud
A
- A private cloud is owned by
one organization and is not
shared with any other
organization - The private cloud can either
be created and maintained
by the organization itself or it
can outsource these tasks to
a third-party
5
Q
Benefits and drawbacks of cloud computing
A
Benefits:
* Relatively less technical
knowledge required and easy
to implement
* Flexibility: Cloud Can Be
Scaled To Match The
Organization’s Growth
Drawback:
* Cannot access the
resources/data stored on the
cloud, if there are bandwidth
issues
* Poor data privacy, since there
may be data leakage in the
multi-tenant architecture
(public clouds)
6
Q
World Wide Web (WWW)
A
- Collection of web pages stored on websites
- Protocols are used to transmit data across the WWW
7
Q
Internet (Interconnected network)
A
- Massive, open network of networks
- Uses TCP/IP protocol, which uses IP addresses to
identify devices connected to the internet - Access provided by Internet Service Provider
Communication used: wired, radio and satellite
8
Q
Router in a network
A
- Connects two networks together which may operate
on different protocols - Allows internal connections between LANs OR allows
external connection from the main LAN to a WAN - Router acts as gateway & firewall
- Usually will be attached to server or switch in a LAN
- Router translates private IP addresses to public IP
addresses AND vice versa.
9
Q
LAN-supporting hardware
A
- Switch: Connected to all devices in a LAN and can
simultaneously broadcast information to all devices - Server: device/software provides specific function for
computers in the network
10
Q
Network Interface Card (NIC)
A
- Provides each device (an end-system) in the wired
LAN with a unique (MAC) address to uniquely
identify it on the network - Allows each individual device to connect to
network
11
Q
Wireless Network Interface Card (WNIC)
A
Provides
each end-system of a wireless (WiFi) LAN a unique
network address to identify it.
12
Q
Wireless Access Points (WAP)
A
- Allows devices to connect to the LAN via WiFi
(wireless radio communication) instead of using a
cable - Usually built into router
13
Q
Cables
A
A wired transmission medium that allows
communication in wired networks
14
Q
Bridge
A
- Connects two LANs which work use the same
protocol, which can be two segments of the same
network - Stores network addresses for all devices (endsystems) between the 2 networks
- A bridge looks for the receiving device before it
sends the message.
15
Q
Repeater
A
- Connects two cables
- Regenerates the sent data signal over the same
network before the signal weakens (attenuation)
to prevent it from being corrupted
16
Q
Internet-supporting hardware
A
- Modems
- PSTN (Public Switched Telephone Network)
- Dedicated lines
- Cell phone network
17
Q
Modems
A
- Allows a device to connect to the Internet via a
telephone line. - A transmitter uses a modem to convert digital
signals (from the transmitting device) to analogue
signals that are then sent down the telephone
line. - A receiver uses a modem on the other end to
convert the analogue signals to digital signals so
the receiving device can understand the data.
18
Q
PSTN (Public Switched Telephone Network)
A
- Refers to all telephone networks
- Channel used between 2 endpoints for the call
duration via circuit switching - Lines active even during power outage
- Bi-directional communication
19
Q
Dedicated lines
A
- Telecommunication path between endpoints
- Not shared with multiple users; it’s bought/leased
- Able to host websites as well as carry phone calls
- Allows continuous, uninterrupted access on Web
20
Q
Cell phone network
A
- Wireless network spread over land areas divided
into (hexagonal) ‘cells’ - Each cell is served by at least one base station
(transceiver), which uses a different frequency
range, as compared to adjacent cells, to transmit
data - Larger capacity possible since same frequencies
can be used, in non-adjacent cells - Radio waves are usually used for transmission
- Can be broadcast in all directions over a wide area
- Portable transceivers (e.g. mobile phones) are able
to communicate and access internet via base
stations
21
Q
IPv4
A
- 32 bit address, split into 4
blocks by “.” - Each block could have a value
between 0 and 255 (00 to FF
in hex). - E.g.255.0.1.255
22
Q
IPv6
A
- 128 bit address divided into
eight 16-bit blocks by “:”. - Each block can have 4 hex
values ranging from 0000 to
FFFF - IPv6 can be shortened by
removing >=2 blocks
containing solely
zeroes - E.g.2001:0db8:85a3::8a
2e:0070:7334
23
Q
IPv4 functionality
A
Each IP address has 2 parts:
* Network Identifier (netID)
* Identifies the network to which the host (device) is
connected to
* Host Identifier (hostID): Identifies the host within
the network
- ‘Classfull’ addressing used for IPv4 where different bit
lengths for identification and impose restrictions on
available address
24
Q
Subnetting
A
- Practice of dividing a network into two or more
networks - IP addresses are broken down to 3 parts by not
changing the netID but partitioning the host ID into a
subnet ID and host ID - These subnet ID bits are used to identify each subnet
within the network. - Subnet masks are numbers that hides (masks) the
netID of a system’s IP address and leaves only the
host part as the machine identifier, allowing data to
be routed within the subnet to the appropriate host.
25
Q
Public and Private IP address
A
- Public IP is provided by the ISP while Private IP issued
by the LAN’s router - Public IP is unique and can be across the internet
whereas Private IP is only unique within LAN and
hence can only be accessed within LAN - NAT (Network address translation) required for
private IP addresses to access internet directly. - Private IP more secure than public IP, since they are
not directly accessible on the Internet and are hidden
by NAT - Range of IP addresses used for private IP addressing
can never be assigned to public IP addresses
26
Q
Static IP addresses
A
- IP address never changes.
- Static IP addresses are useful
when websites need to
remember a device for a long
time. Eg) VPNs whitelisting - Faster upload/download
speeds
27
Q
Dynamic IP addresses
A
- IP address will change at
regular time periods. - Dynamic IP address is
relatively more secure, hence
used where data privacy is
important - Maintaining cost of dynamic
IP address is lesser
28
Q
URL (Uniform Resource Locator)
A
- Unique reference address for the exact location of an
internet resource on the WWW - Protocol: enables browser to know what protocol is used
to access info in domain - Hostname: Domain name
- Location of server: path
- Domain Name Service (DNS)
- Naming system used for computers or resources
having internet connection - Consists of a hierarchy of DNS servers which have a
URLs database of and their corresponding IP
addresses
