4.9 Fundamentals of communication and networking

serial data transmission

A method of transmitting data one bit at a time over a single channel or wire, commonly used in communications where long distances are involved.

parallel data transmission

A method of transmitting multiple bits simultaneously over multiple channels or wires, allowing for faster data transfer rates, typically used in short-distance communication.

synchronous data transmission

A method of data transmission where data is sent at regular intervals, synchronized with a clock signal, ensuring that both sender and receiver are aligned in timing.

asynchronous data transmission

A method of data transmission where data is sent without a synchronized clock signal, allowing for more flexible timing between sender and receiver, often using start and stop bits to indicate data boundaries.

start bits

Special bits used in asynchronous data transmission to indicate the beginning of a data packet, allowing the receiver to detect when to start reading the incoming data.

stop bits

Special bits used in asynchronous data transmission to signal the end of a data packet, allowing the receiver to know when to stop reading the incoming data.

baud rate

The rate at which symbols are transmitted over a communication channel, typically measured in baud (symbols per second), indicating the speed of data transmission.

bit rate

The number of bits transmitted per second in a digital communication channel, often used to measure the speed of data transmission.

bandwidth

The maximum rate of data transfer across a network path, typically measured in bits per second (bps), indicating the capacity of the communication channel.

latency

The time taken for a data packet to travel from the source to the destination, typically measured in milliseconds. It affects the responsiveness of a network.

protocol

A set of rules and conventions for data communication between devices in a network, ensuring proper data exchange and interpretation.

difference between baud and bit rate

Baud rate measures the number of signal changes or symbols per second, while bit rate measures the number of bits transmitted per second. In some cases, one baud can represent multiple bits, depending on the encoding scheme used.

relationship of bit and baud rate

bit rate quantifies the number of bits transmitted per second, while baud rate measures the number of signal changes per second. Depending on the modulation technique, one baud can correspond to multiple bits.

physical star topology

A network topology where devices are connected to a central hub or switch, allowing for easy management and isolation of network segments.

logical bus network topology

A network topology where all devices are connected to a single central cable, known as the bus, allowing data to travel in both directions. It is simple and cost-effective but can lead to performance issues if the bus becomes overloaded.

difference between physical star and logical bus networks

A network physically wired in star topology can behave logically as a bus network by using a bus protocol and appropriate physical switching.

what does a logical bus network topology do

A logical bus network allows all devices connected to the bus to communicate with each other by sending data packets along a single central cable, facilitating bidirectional data flow. It enables devices to share information efficiently, though it may experience collisions if multiple devices transmit simultaneously.

what does a physical star topology do

A physical star topology connects all devices to a central hub or switch, allowing each device to communicate directly with the hub, which manages data traffic and improves network performance.

peer to peer networking

A network architecture where each device can act as both a client and a server, allowing direct communication and resource sharing among devices without a central server.

client-server network

A network architecture that separates client devices from a central server, where clients request resources or services from the server, which processes the requests and delivers the necessary data.

purpose of wifi

A wireless local area network that is based on international standards.

Used to enable devices to connect to a network wirelessly.

Wireless network adapter.

A hardware component that allows a device to connect to a wireless network, facilitating communication and data transfer without physical cables.

wireless access point

A device that allows wireless devices to connect to a wired network using Wi-Fi or other standards, extending the network's coverage.

how are wireless networks secured

-strong encryption of transmitted data using WPA (Wifi Protected Access)/WPA2,

- SSID (Service Set Identifier) broadcast disabled,

-MAC (Media Access Control) address allow list.

what is CSMA/CA

Carrier Sense Multiple Access with Collision Avoidance is a network protocol used in wireless networks to manage how devices access the communication medium and prevent data collisions.

what is RTS/CTS

RTS/CTS (Request to Send/Clear to Send) is a network protocol used in wireless communication to minimize collisions by reserving the channel before data transmission, allowing devices to signal their intent to send data.

purpose of ssid

The SSID (Service Set Identifier) serves as the name of a wireless network, allowing devices to identify and connect to the correct network. It is essential for distinguishing between multiple networks in the same vicinity.

structure of the internet

The structure of the internet refers to the interconnected network of servers, routers, and devices that communicate using standardized protocols, enabling data exchange and connectivity across the globe.

packet switching

Packet switching is a method of data transmission in which data is broken into smaller packets that are sent independently over the network and reassembled at the destination, improving efficiency and reliability.

routers

A mode of data transmission in which a message is broken into a number of parts which are sent independently, over whatever route is optimum for each packet, and reassembled at the destination.

router

connect computers and other devices to the Internet. A router acts as a dispatcher, choosing the best route for your information to travel

components of a packet

header

payload

header

source address, a destination address, protocol, and packet number.

gateway

a network node used in telecommunications that connects two networks with different transmission protocols together

how routing is achieved across the Internet.

• Step 1: Send packet to router. Computers send the first packet to the nearest router.

• Step 2: Router receives packet. ...

• Step 3: Router forwards packet. ...

• Step 4: Final router forwards message.

url

the address of a unique resource on the internet.

fqdn

fully qualified domain name that specifies the exact location within the domain name system (DNS) by specifying the hostname, domain name and top-level domain (TLD)

ip address

a unique address that identifies a device on the internet or a local network

how are domain names organized

via subdomains which are subordinate levels of the Domain Name System root domain. deserts from right to left

function of a dns

translating domain names into a specific IP address so that the initiating client can load the requested Internet resources.

services provided by internet registries

Internet number resources to Internet service providers (ISPs) and other organisations in our geographical service region

firewalls

a network security device that monitors and filters incoming and outgoing network traffic based on an organization's previously established security policies.

proxy server

a system or router that provides a gateway between users and the internet

stateful inspection

a technology used by stateful firewalls to determine which packets to allow through the firewall

public/private keys

A message gets encrypted by a public key, which is available to everyone, and can only be decrypted with its unique private key,which is only available to its owner

digital certificates

a file or electronic password that proves the authenticity of a device, server, or user through the use of cryptography and the public key infrastructure (PKI)

trojans

a type of malware that downloads onto a computer disguised as a legitimate program

worms

a type of malware that can automatically propagate or self-replicate without human interaction, enabling its spread to other computers across a network

virus

a type of malicious software, or malware, that spreads between computers and causes damage to data and software

digital signiture

an electronic, encrypted stamp of authentication on digital information such as messages

tcp/ip

application, transport, network, link

application (tcp/ip)

Selects and uses the ​correct protocol​ to transmit data. The layer interacts with the user with ​application software​ like a web browser

like sending a message across the internet

transport (tcp/ip)

Establishes what’s called a ​virtual path​: an ​end to end connection between the sender and the receiver. The layer then ​splits the transmission into packets​.

network (tcp/ip)

Provides the ​correct IP addresses​ for each packet’s source and destination.

link (tcp/ip)

controls​ physical connections between pieces of hardware​ in a network. Adds ​MAC addresses​ to packets which it receives from the network layer

Mac adress

a unique, 12-character alphanumeric attribute that is used to identify individual electronic devices on a network

well known ports

port numbers from 0 to 1023 are reserved for common TCP/IP applicationsand are called well-known ports. The use of well-known ports allows client applications to easily locate the corresponding server application processes on other hosts.

client ports

assigned to a client-side application or process when it initiates a network connection to a server

difference between client ports and well known ports

While the listening port number of a server is well defined (IANA calls these the well-known ports), the client's port number is often chosen from the dynamic port range

types of protocols

• FTP (File Transfer Protocol)

• HTTP (Hypertext Transfer Protocol)

• HTTPS (Hypertext Transfer Protocol Secure)

• POP3 (Post Office Protocol (v3))

• SMTP (Simple Mail Transfer Protocol)

• SSH (Secure Shell).

ftp client software

a standard network protocol used for the transfer of files from one host to another over a TCP-based network, such as the Internet

anonymous ftp and non-anonymous

anonymous File Transfer Protocol (FTP) enables remote users to use the FTP server without an assigned user ID and passwor

Ssh remote management

provides encrypted connections between a client and a remote device and enables an encrypted bidirectional communication path between two systems

how an SSH client is used to make a TCP connection to a remote port for the purpose of sending commands to this port using application level protocols such as GET for HTTP, SMTP commands for sending email and POP3 for retrieving email.

ssh security log in

you need the Internet Protocol (IP) address or hostname of the remote server and a valid usernam

role of an email server in retrieving and sending email.

responsible for the centralised management of emails that are sent and received by users within a network.

role of a web server in serving up web pages in text form.

display website content through storing, processing and delivering webpages to users

the role of a web browser in retrieving web pages and web page resources and rendering these accordingly.

the browser retrieves the website's HTML, CSS, and JavaScript files from the server

parts of a up address

network identifier

host identifier

how is a network divided up

subnets

subnet mask

a 32-bit address that segregates an IP address into network bits that identify the network and host bits that identify the host device operating on that network

ip address standards

v4 and v6

why was v6 introduced

o reduce the vibrations compared with the V4 engine.

what’s the difference between routable and non routable ip addresses

Routable addresses are utilized for hosting public-facing services, such as web servers, email servers, and online applications. Non-routable addresses are used for private network communication, including local file sharing, printer access, and internal messaging.

purpose and function of the DHCP system

automatically provides an Internet Protocol (IP) host with its IP address and other related configuration information such as the subnet mask and default gateway

NAT

network address translation : the process of mapping an internet protocol (IP) address to another by changing the header of IP packets while in transit via a router

port forwarding

allows remote servers and devices on the internet to be able to access devices that are on a private network

client server model

Client sends a request message to server, server responds to request by replying with a response message to client.

Websocket protocol

a computer communications protocol, providing a simultaneous two-way communication channel over a single Transmission Control Protocol (TCP) connection

CRUD

create

retreave

update

delete

what does rest allow crud to do

enable;es crud to be mapped out to database functions

rest

• GET → SELECT

• POST → INSERT

• DELETE → DELETE

• PUT → UPDATE.

Compare JSON (Java script object notation) with XML.

XML is more complex and requires a tag structure.

JSON is a data format that extends from JavaScript.

It does not use tags, which makes it more compact

easier to read for humans.

JSON can represent the same data in a smaller file size for faster data transfer.

Compare and contrast thin-client computing with thick-client computing.

Maintaining thick client applications requires regular updates, patches, and troubleshooting on each individual device, which can be time-consuming for IT teams. In contrast, thin client applications are centrally managed, allowing updates and maintenance to be done remotely using the remote management tool.