39 The Internet

Front 1

internet:

Back 1

a global network of networks

Front 2

is the internet the same as the world wide web?

Back 2

no

Front 3

URL:

Back 3

uniform resource locator: a method for identifying the location of resources on the website.

Front 4

what is each part of the web address:

http://www.awebsite.co.uk/index.html

Back 4

http: protocol being used

www. : server being used

awebsite : organisation

co : type of organisation

uk : country code

index.html : file being accessed.

Front 5

Domain name:

Back 5

the recognisable name of a domain on the internet.

Front 6

name what each top-level domain name is:

com

gov

ac

sch

org

net

Back 6

commercial organisation

part of the government

academic institution

organisation of a school

organisation other than commercial business

company providing internet services

Front 7

when the www is typed, what is the domain name called?

Back 7

a fully qualified domain name and is completely unambiguous.

Front 8

IP address:

Back 8

a unique number that identifies devices on a network

Front 9

Domain name server:

Back 9

DNS: a server that contains domain names and associated IP addresses

Front 10

why are some IP addresses private(non-routable) addresses?

Back 10

they are used on a private network, like a home, schools or business. it's used to route data around the network.

Front 11

ports:

Back 11

used to identify a particular process or application on a network. it is a 16 bit number

Front 12

what are these protocols:

HTTP

POP3

SSH

HTTPS

SMTP

Back 12

hypertext transfer protocol: 80

post office protocol: 110

secure shell protocol: 22

hypertext transfer secure protocol: 443

simple mail transfer protocol: 25

Front 13

how to ports work?

Back 13

1) when a client sends a request to a server using a well-known port,

2) the server needs to respond by using the client port then the other port.

3) therefore, a source port must be sent so the server knows what port to use.

Front 14

Domain name server system:

Back 14

a system of connected domain name servers that provides the IP address of every website on the internet.

Front 15

what is the system called where the private IP addresses is matched with the public ones?

Back 15

Network address translation(NAT)

Front 16

what are the advantages of NAT?

Back 16

1: only the public IP address needs to be registered with the DNS system

2: increased level of security is the privates are not being broadcast over the internet.

Front 17

what is in a translation table?

Back 17

the tracking of connections and mappings between private IP addresses and port numbers with the public address.

Front 18

how does NAT work?

Back 18

1) the client sends packets to request some data from a server. they have the private IP address and port number so it can be sent back.

2) the router replaces the private port and IP address, with its external IP address and generated port number. the private addresses is stored in a translation table with the public addresses

3)when data is sent back, the port number on the packet is checked in the translation table

4) if there is a match, the public address in the packet is replaced with the private address from the translation table. it then goes into the private network back to the original sender.

5) if not, the packet is discarded as it could be a potential threat.

Front 19

port forwarding:

Back 19

a method of routeing data through additional ports

Front 20

when is port forwarding used?

Back 20

when a server provides services to the public from a private network

Front 21

how does port forwarding work?

Back 21

the router can be programmed that if a request is made to its router and it has a certain port number, then it can be forwarded to a device with a specific IP address within a network.

Front 22

socket:

Back 22

an endpoint of a communication flow across a computer network.

Front 23

what do sockets do?

Back 23

they are used to communicate the other end of the communication so that a connection can be established. for example,192.168.0.1:80 is a socket that a server will listen to. with the request, the socket address will have the clients port.

Front 24

subnet Masking:

Back 24

a method of dividing a network into multiple smaller networks.

Front 25

why is subnet masking used?

Back 25

it is easier to manage and to make it more efficient when routeing data. this means that if data is sent from one client to another, then the subnet will say whether it's on the same network or a different network.

Front 26

Gateway:

Back 26

a node on a network that acts as a connection point to another network with different protocols.

Front 27

why should we use the IPV6 addresses than IPV4?

Back 27

as the internet is expanding rapidly, there is not enough unique addresses that can be used for each device. so 128 bits with hex numbers is used to increase the amount of IP addresses.

Front 28

Dynamic Host Configuration Protocol:

Back 28

(DHCP): a set of rules for allocating locally unique IP addresses to devices as they connect to a network.

Front 29

what is the difference between static and dynamic IP addresses?

Back 29

static: are assigned to a device and never change

dynamic: allocated every time a device connects to a network.

Front 30

how does the allocation of IP addresses happen?

Back 30

1) it is done automatically by an application

2) the application looks for available IP addresses from its pool of addresses and allocates it to the device.

Front 31

how does the domain server system work?

Back 31

1) the client with the domain name is sent to its local DNS.

2) the DNS then tries to match the domain name from the request with the IP address unique to that name.

3) if there is a match, then the IP address is sent back to the client and then used to reach the specific server.

4) if there is no match, the DNS will send a request to other DNS to see if they have the match needed. if so, then its sent back to the original DNS and then back to the client.

Front 32

Internet registries:

Back 32

organisations who allocate and administer domain names and IP addresses

Front 33

what is the hierarchical structure of internet registries, and their names?

Back 33

ICANN - the internet corporation for assigned names and numbers

IANA - internet assigned numbers authority

RIR - Regional Internet Registries

NIR - National Internet Registries

LIR - Local Internet Registries

Front 34

Regional internet Registry:

Back 34

one of five large organisations that allocate and administer domain names and IP addresses in different parts of the world.

Front 35

how is data sent through a WAN?

Back 35

the packets that are sent travel through multiple nodes to get to the receiver and vice versa.

Front 36

Routing:

Back 36

a process of directing packets of data between networks.

Front 37

how does routeing work?

Back 37

it finds the optimum route between the sender and receiver. data packets are sent to the next router in the path and is referenced in a routeing table. other possible routes are also stored in the routeing table.

Front 38

Packet switching:

Back 38

a method for transmitting packets of data via the quickest route on a network.

Front 39

what does the header contain?

Back 39

MAC address of sender and receiver

sender and receiver IP address

protocols being used

packet or sequence number

Front 40

what does the body contain?

Back 40

the actual data

Front 41

what does the footer contain?

Back 41

a checksum

Front 42

Checksum:

Back 42

a method of checking the integrity of data by calculating a sum based on the data being sent.

Front 43

why can each packet go through a different route?

Back 43

the packets contain a sequence number that is used to reassemble them.

Front 44

what's the use of sending packets through different routes?

Back 44

this means that the packets can go through the least congested and therefore quickest route. it is also secure as it's not the same route.