What Everyone Must know about Networking?

Osama Shakeel

35 min readFeb 17, 2022

Table of Content:

1.Networking Basics

2.Network Types

3.Network Topologies

4.Network Devices

5.Transmission Modes

6.Digital Transmission

7.Transmission Media

8.How Internet Works

9.IP Addressing IPv4 & IPv6

10.Subnet Mask, MAC, DHCP & DNS

11.WLAN & WPAN Networks

12.OSI Model

13.TCP/IP Model

14.TCP & UDP

15.ARP & RARP

16.CSMA/CA & CSMA/CD

17.Proxy & VPN

18.Server & Datacenter

19. Network Security

20. NAS & NAT

21. RAID (Redundant Array of Independent Disk)

22. Sharing Folder in Network

23. TELNET in Network

24. Remote Desktop Connection

25. Windows Remote Assistance

26. FTP in Network

27. Configuring Network

28. Configuring Router

29. Protocols You need to know

30. Networking Commands you must know

The Networking Article of Your Dreams:

NETWORK:

A network consists of two or more computers that are linked in order to share resources, exchange files or communication. The computers on a network may be linked through cables, telephone lines, radio waves, satellites, or infrared light beams.

NETWORKING:

Networking, also known as computer networking, is the practice of transporting and exchanging data or information & having communication between connected nodes over a shared medium.

INTERNET:

Collection of Networks is Internet. The first workable prototype of the Internet came in the late 1960s with the creation of ARPANET, or the Advanced Research Projects Agency Network. Which was designed for US Defence. Later Sir Tim Berners lee introduced WWW concept and starts web.

MESSAGE / TOKEN

When one of the systems on the network has the “token,” it can send information to the other computers. Since there is only one token for each token-ring network, only one computer can send data at a time. It verify that the target receiver is present or not before sending the data from sender.

NETWORK ARCHITECTURE:

Peer to Peer Model

2. Client-Server Model

Peer to Peer Model:

Client-Server Model:

Peer to Peer VS Client-Server Model:

Basic Types of Networks

1. Personal Area Network (PAN)

2. Local Area Network (LAN)

3. Wide Area Network (WAN)

4. Wireless Local Area Network (WLAN)

5. Campus Area Network (CAN)

6. Metropolitan Area Network (MAN)

7. Storage Area Network (SAN)

8. Enterprise Private Network (EPN)

9. Virtual Private Network (VPN)

Personal Area Network (PAN)

PAN is the most basic type of computer network. This network is restrained to a single person, PAN offers a network range of 10 meters from a person to the device providing communication.

Local Area Network (LAN)

LAN is the most frequently used network. A LAN is a computer network that connects computers together through a common communication path, contained within a limited area, A LAN encompasses two or more computers connected over a server. The two important technologies involved in this network are Ethernet and Wi-fi.

3. Wide Area Network (WAN)

WAN is a type of computer network that connects computers over a large geographical distance through a shared communication path. It is not restrained to a single location but extends over many locations. WAN can also be defined as a group of local area networks that communicate with each other.

4. Wireless Local Area Network (WLAN)

WLAN is a type of computer network that acts as a local area network but makes use of wireless network technology like Wi-Fi. This network doesn’t allow devices communicating over physical cables like in LAN, but allows devices to communicate wirelessly.

5. Campus Area Network (CAN)

CAN is bigger than a LAN but smaller than a MAN. This is a type of computer network which is usually used in places like a school or college. This network covers a limited geographical area that is, it spreads across several buildings within the campus.

6. Metropolitan Area Network (MAN)

A MAN is larger than a LAN but smaller than a WAN. This is the type of computer network that connects computers over a geographical distance through a shared communication path over a city, town or metropolitan area.

7. Storage Area Network (SAN)

SAN is an abbreviation of the Storage Area Network. Storage Area Network is a dedicated, specialized, and high-speed network which provides block-level data storage. It delivers the shared pool of storage devices to more than one server.

8. Enterprises Private Network (EPN)

EPN is a type of computer network mostly used by businesses that want a secure connection over various locations to share computer resources.

9. Virtual Private Network (VPN)

A virtual private network extends a private network across a public network and enables users to send and receive data across shared or public networks as if their computing devices were directly connected to the private network.

Network Topologies

Basic Types of Network Topologies

Bus Topology
Star Topology
Ring Topology
Tree Topology
Mesh Topology
Hybrid Topology
Daisy Chain Topology

1. Bus Topology

The bus topology is designed in such a way that all the stations are connected through a single cable known as a backbone cable. The backbone cable is considered as a “single lane” through which the message is broadcast to all the stations.

2. Star Topology

Star topology is an arrangement of the network in which every node is connected to the central hub, switch or a central computer. The central computer is known as a server, and the peripheral devices attached to the server are known as clients.

3. Ring Topology

Ring topology is like a bus topology, but with connected ends. The node that receives the message from the previous computer will retransmit to the next node.

The data flows in a single loop continuously known as an endless loop. The most common access method of the ring topology is token passing.

4. Tree Topology

Tree topology combines the characteristics of bus topology and star topology. A tree topology is a type of structure in which all the computers are connected with each other in hierarchical fashion. If the central hub gets fails the entire system fails.

5. Mesh Topology

In this type of topology, a host is connected to one or multiple hosts.This topology has hosts in point-to-point connection with every other host or may also have hosts which are in point-to-point connection to few hosts only.

Two types Full Mesh Topology & Partially Mesh.

6. Hybrid Topology

The combination of various different topologies is known as Hybrid topology. When two or more different topologies are combined together is termed as Hybrid topology and if similar topologies are connected with each other will not result in Hybrid topology.

7. Daisy Chain Topology

This topology connects all the hosts in a linear fashion. Similar to Ring topology, all hosts are connected to two hosts only, except the end hosts. Means if the end hosts in daisy chain are connected then it represents Ring topology.

Network Devices

Basic Types of Network Devices

NIC Card
Hub
Switch
Router
Repeater
Modem
Bridge
Gateway
Access Point
Server

1. NIC Card

NIC or network interface card is a network adapter that is used to connect the computer to the network. bit has a unique id that is written on the chip, and it has a connector to connect the cable to it. The cable acts as an interface between the computer and router.

2. Hub

A hub is basically a multiport repeater. A hub connects multiple wires coming from different branches, for example, the connector in star topology which connects different stations. Hubs cannot filter data, so data packets are sent to all connected devices. they do not have the intelligence to find out the best path for data packets which leads to inefficiencies and wastage.

3. Switch

A switch is a hardware device that connects multiple devices on a computer network. A Switch contains more advanced features than Hub. A Switch does not broadcast the message to the entire network like Hub. It determines the device to whom the message is to be transmitted. Therefore, we can say that switch provides a direct connection between the source and destination. It increases the speed of the network.

4. Router

A router is a device like a switch that routes data packets based on their IP addresses. It is used to receive, analyze and forward the incoming packets to another network. A router forwards the packet based on the information available in the routing table.

5. Repeater

Its job is to regenerate the signal over the same network before the signal becomes too weak or corrupted so as to extend the length to which the signal can be transmitted over the same network. An important point to be noted about repeaters is that they do not amplify the signal. When the signal becomes weak, they copy the signal bit by bit and regenerate it at the original strength.

6. Modem

It stands for Modulator/Demodulator. It converts the digital data into an analog signal over the telephone lines. It allows the computer to connect to the internet over the existing telephone line.

• Standard PC modem or Dial-up modem

• Cellular Modem

Cable modem

7. Bridge

A bridge is a repeater, with add on the functionality of filtering content by reading the MAC addresses of source and destination. It is also used for interconnecting two LANs working on the same protocol. It has a single input and single output port.

Types of Bridges

v Transparent Bridge: -

These are the bridge in which the stations are completely unaware of the bridge’s existence

v Translational Bridge: -

A type of bridge that interconnects two different types of LAN protocols, such as Ethernet and Token Ring.

v Source Routing Bridge: -

A type of bridge that interconnects 2 different types of LAN protocols, such as Ethernet and Token Ring.

v Remote type Bridge: -

A device that connects two LAN segments together that are in geographically dispersed locations. It connects LANs via a WAN.

8. Gateway

A gateway is a network node that forms a passage between two networks operating with different transmission protocols.

The gateway converts information, data or other communications from one protocol or format to another. A router may perform some of the functions of a gateway.

9. Access Point

An access point is a device that creates a wireless local area network, or WLAN, usually in an office or large building. An access point connects to a wired router, switch, or hub via an Ethernet cable and device that allows other Wi-Fi devices to connect to a wired network.

10. Server

A server is a computer or system that provides resources, data, services, or programs to other computers, known as clients, over a network. In theory, whenever computers share resources with client machines they are considered servers. Typical servers are database servers, file servers, mail servers, print servers, web servers, game servers, and application servers.

Transmission Modes

The way in which data is transmitted from one device to another device is known as transmission mode. Each communication channel has a direction associated with it, and transmission media provide the direction. Therefore, the transmission mode is also known as a directional mode.

Simplex-mode Transmission

In Simplex mode, the data flows in one direction. This transmission mode is not very popular as mainly communications require the two-way exchange of data. Keyboard and Monitor are the examples of the simplex mode as a keyboard can only accept the data from the user and monitor can only be used to display the data on the screen. The main advantage of the simplex mode is that the full capacity of the communication channel can be utilized during transmission.

Half-Duplex Transmission

In a Half-duplex channel the station can transmit and receive the data as well. Messages flow in both the directions, but not at the same time. A Walkie-talkie is an example of the Half-duplex mode. In Walkie-talkie, one party speaks, and another party listens. After a pause, the other speaks and first party listens. The entire bandwidth of the communication channel is utilized in one direction at a time.

Full-Duplex Transmission

In Full duplex mode, the data flow in both the directions. Both the stations can send and receive the message simultaneously. The Full-duplex mode is the fastest mode of communication between devices. The most common example of the full-duplex mode is a telephone network. When two people are communicating with each other by a telephone line, both can talk and listen at the same time.

Digital Transmission

Data can be represented either in analogue or digital form. The computers used the digital form to store the information. Therefore, the data needs to be converted in digital form so that it can be used by a computer.

Digital to Digital Conversion?

Digital-to-digital encoding is the representation of digital information by a digital signal. When binary 1s and 0s generated by the computer are translated into a sequence of voltage pulses that can be propagated over a wire, this process is known as digital-to-digital encoding.

Three forms:

Unipolar

Digital transmission system sends the voltage pulses over the medium link such as wire or cable. The polarity of each pulse determines whether it is positive or negative. In Unipolar Encoding, ‘1’ is considered as a high voltage and ‘0’ is considered as a zero voltage.

Polar

Polar encoding is an encoding scheme that uses two voltage levels: one is positive, and another is negative. By using two voltage levels, an average voltage level is reduced, and the DC component problem of unipolar encoding scheme is alleviated.

• Polar NRZ

• Polar RZ

Polar NRZ

Polar RZ

Bipolar

If the first 1 bit is represented by positive amplitude, then the second 1 bit is represented by negative voltage, third 1 bit is represented by the positive amplitude and so on. This alternation can also occur even when the 1bits are not consecutive.

AMI (Alternate Mark Inversion) The Binary 0 gets represented by a neutral voltage. On the other hand, alternating negative and positive voltages represent the Binary 1s.

Pseudo ternary Here, we encode the bit 1 as a zero voltage, while we encode the bit 0 as alternating negative and positive voltages. It means that this one is exactly the opposite of the AMI scheme. For example, Data = 010010.

Transmission Media

Transmission media is a communication channel that carries the information from the sender to the receiver. Data is transmitted through the electromagnetic signals.

Bandwidth: -

The greater the bandwidth of a medium, the higher the data transmission rate of a signal.

Transmission impairment: — When the received signal is not identical to the transmitted one due to the transmission impairment. quality of the signals will get destroyed due to transmission impairment.

Interference: — An interference is defined as the process of disrupting a signal when it travels over a communication medium on the addition of some unwanted signal.

Attenuation means the loss of energy, strength of the signal decreases with increasing the distance

Distortion occurs when there is a change in the shape of signal. This type of distortion is examined from different signals having diff frequencies.

Noise is When data is travelled over a transmission medium, some unwanted signal is added to it

Classification of Transmission Media?

Guided Media

It is defined as the physical medium in which the signals are transmitted. also known as Bounded media.

What is a Cable?

An electrical cable is an assembly of one or more wires running side by side or bundled, which is used to carry electric current. A cable assembly is the composition of one or more electrical cables and their corresponding connectors.

1. Twisted Pair Cable

Twisted-pair cable is a type of cabling that is used for telephone communications and most modern Ethernet networks. A pair of wires forms a circuit that can transmit data. The pairs are twisted to provide protection against crosstalk, the noise generated by adjacent pairs having RJ-11 & RJ-45 Jacks.

Two Types :-

STP (Shielded Twisted Pair Cable)

2. UTP (Unshielded Twisted Pair Cable)

Ethernet Port

• Connects to a network and high speed Internet upto 100baseT.

• Known as RJ-45 Port which use RJ-45 Jack as Interface

This port resides on an Ethernet Card.

What are RJ connectors?

RJ Connectors are a family of push-and-click connectors for twisted-pair wiring in telephone and network wiring. RJ stands for Registered Jack. RJ types define both a jack or receptacle (female) and a plug (male) type of connector.

The most common types of RJ connectors are as follows:

RJ-11 connector: A 4-wire or 6-wire telephone-type connector

RJ-45 connector: An 8-wire telephone-type connector

RJ-48 connector: An 8-wire telephone-type connector

2. Patch Cables

Patch cable is often called a straight through cable. In other words, patch cable does not change or swap along its way. Both ends use the same wiring standard: T-568A or T-568B.

Straight Tip vs Crosstalk

Patch Cables vs. Crossover Cable: When to Use?

Scenario 1: PC to PC

Scenario 2: PC to Switch to PC

Scenario 3: PC to Switch to Switch to PC

3. Coaxial Cable

Coaxial cable is commonly used by cable operators, telephone companies, and internet providers around the world to convey data, video, and voice communications to customers. It has also been used extensively within homes.

BNC Connector

Bayonet Neill–Concelman BNC connector is a series of connectors used for connecting thinnet coaxial cabling to various networking components.

4. Optic Fibre Cable

Fibre optics is a modern technology used mostly in the telecommunication industry to transmit information digitally as pulses of light through strands of fibre made of glass.Also known as Optical fibres, these strands are about the diameter of a human hair follicle. When bundled into an optical fibre cable, they can transmit data in volumes faster than other mediums over really long distances.

Subscriber Connector SC

This Connector is for structural cabling it is used for high speed

And for single mode fibre cabling

Straight Tip ST

This Connector is for structural cabling it is used for high speed

And for Multi mode fibre cabling

Unguided Media

They transmits the electromagnetic waves without using physical medium.it is also known as wireless transmission.

Radio Waves

Radio waves at lower frequencies can travel through walls whereas higher RF can travel in straight line and bounce back.The power of low frequency waves decreases sharply as they cover long distance. High frequency radio waves have more power. The range in frequencies of radio waves is from 20kHz 300Hz.

Applications

• television and FM and AM radio broadcasts

• military communications

Radio Control Car

Microwaves

• Microwaves travel in straight lines, and so the transmitter and receiver stations should be accurately aligned to each other. Microwaves are unidirectional

• Microwaves electromagnetic waves having frequency in the range from 1GHz to 1000 GHz.

Applications

• Cellular phones

• 3G, 4G or 5G Network

• Satellites

• Wireless LAN

Wireless PAN

Infrared

Infrared waves are those between the frequencies 300GHz and 400THz in the electromagnetic spectrum. Their wavelengths are shorter than microwaves but longer than visible light. Infrared propagation is line of sight. Range lies bwtween 300 GHz to 400 THz.

Applications

• Remote controls for television, stereos and other appliances.

• Wireless modem, keyboard, mouse, printer etc

• Night vision systems

• Motion detectors

How Internet Works

IP Addressing IPv4 & IPv6

What is IP Address?

An Internet Protocol address is a numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication. An IP address serves two main functions: host or network interface identification and location addressing.

IP Addressing IPv4

• An IP address basically a 32-bit address that uniquely universally defines connection of host or a router to the Internet. IP address is unique.

• Introduced by IANA (Internet Assigned Numbers Authority).

• 32 bit is divided into 4 equal parts of 8–8 bits separated by dotted decimal notation. It is in the range of minimum 0.0.0.0 to 255.255.255.255.

• Each 8 bit group is known by OCTET.

Various IP classes

IP has five different classes differentiated by characteristics.

◦ Class-A ranges from 0 to 127

◦ Class-B ranges from 128 to 191

◦ Class-C ranges from 192 to 223

◦ Class-D ranges from 224 to 239

◦ Class-E ranges from 240 to 255

First Octet is defines the class of particular IP e.g. — 128.11.3.31 is follow in class –B

127.0.0.0 to 127.255.255.255 is a range of look back IP.

Class-A

Class A addresses only include IP starting from 1.x.x.x to 126.x.x.x only. The IP range 127.x.x.x is reserved for loopback IP addresses.

The default subnet mask for Class A IP address is 255.0.0.0 which implies that Class A addressing can have 126 networks (27–2) and 16777214 hosts (224–2).

Class B

Class B IP Addresses range from 128.0.x.x to 191.255.x.x. The default subnet mask for Class B is 255.255.x.x.

Class B has 16384 (214) Network addresses and 65534 (216–2) Host addresses.

Class C

Class C IP addresses range from 192.0.0.x to 223.255.255.x. The default subnet mask for Class C is 255.255.255.x. Class C gives 2097152 (221) Network addresses and 254 (28–2) Host addresses.

Class-D

Class D has IP address range from 224.0.0.0 to 239.255.255.255. Class D is reserved for Multicasting. In multicasting data is not destined for a particular host, that is why there is no need to extract host address from the IP address, and Class D does not have any subnet mask.

Class-E

This IP Class is reserved for experimental purposes only for R&D or Study. IP addresses in this class ranges from 240.0.0.0 to 255.255.255.254. Like Class D, this class too is not equipped with any subnet mask.

IP Addressing IPv6

• An IP address basically a 128-bit address that uniquely universally defines connection of host or a router to the Internet. IP address is unique.

• Introduced by IANA (Internet Assigned Numbers Authority).

• total of 4,294,967,296 unique IP addresses can be assigned to hosts.

• IP is like 2001:db8:1234::f350:2256:f3dd/64

• It supports Unicast. Telecast & Multicast.

It doesn’t have Classes like ipv4

Subnet Mask, MAC, DHCP & DNS

What is Subnet Mask?

A subnet mask is a 32-bit number that segments an existing IP address in a TCP/IP network. It is used by the TCP/IP protocol to determine whether a host is on the local subnet or on a remote network. Subnet mask divides the IP address into a network address and host address, hence to identify which part of IP address is reserved for the network and which part is available for host use.

MAC Address

The Media Access Control (MAC) address is just as important as the IP address. The MAC address is a unique value associated with the network adapter (NIC). MAC addresses are known as the hardware addresses or physical addresses. They uniquely identify the adapter on the LAN.

MAC Address

DHCP

● Dynamic Host Configuration Protocol (DHCP)

○ From 1993

○ An extension of BOOTP, very similar to DHCP

○ Same port numbers as BOOTP

○ Extensions:

■ Supports temporary allocation (“leases”) of IP addresses

■ DHCP client can acquire all IP configuration parameters needed to operate

○ DHCP is the preferred mechanism for dynamic assignment of IP addresses

○ DHCP can interoperate with BOOTP clients.

APIPA

APIPA stands for Automatic Private IP Addressing (APIPA). It is a feature or characteristic in operating systems (eg. Windows) which enables computers to self-configure an IP address and subnet mask automatically when their DHCP(Dynamic Host Configuration Protocol) server isn’t reachable

DNS

DNS stands for Domain Name System. DNS is a service that translates the domain name into IP addresses. This allows the users of networks to utilize user-friendly names when looking for other hosts instead of remembering the IP addresses.

(The inverse domain is used for mapping an address to a name.)

(Generic Domains defines the registered hosts according to their generic behaviour.)

(The format of country domain is same as a generic domain)

Importance of DNS

WLAN & WPAN Networks

WLAN

A wireless LAN is a wireless computer network that links two or more devices using wireless communication to form a local area network within a limited area such as a home, school, computer laboratory, campus, or office building.

Wi-Fi

 What is Wi-Fi

 Short for “Wireless Fidelity”

 A trademark of the Wi-Fi Alliance

 The brand name for products using the IEEE 802.11 family of standards

 Commonly used for “wireless local area network” (WLAN)

WPAN

A personal area network is a computer network for interconnecting electronic devices within an individual person’s workspace. A WPAN provides data transmission among devices such as computers, smartphones, tablets and personal digital assistants.

Bluetooth

 Wireless Personal Area Networks (WPAN)

 Design goal

 Cable replacement

 Low cost

 Low power

 Small size

 For mobile devices

OSI Model

INTRODUCTION

The OSI Model (Open Systems Interconnection Model) is a conceptual framework used to describe the functions of a networking system. The OSI model characterizes computing functions into a universal set of rules and requirements in order to support interoperability between different products and software

OSI MODEL

Data, Protocol & Activities

PHYSICAL LAYER

Physical characteristics of interface and medium (Transmission medium)

Representation of bits (stream of bits (0s or 1s) with no interpretation and encoded into signals)

Line configuration (Point-to-Point, Point-to-Multipoint)

Physical topology

Transmission mode (Simplex, half duplex, full duplex)

DATALINK Layer

Data link layer is responsible for moving frames from one hop (Node) to the next.

Concerned:

Framing (stream of bits into manageable data units) Physical addressing (MAC Address)

Flow Control (mechanism for overwhelming the receiver) Error Control (trailer, retransmission)

Access Control (defining master device in the same link)

NETWORK LAYER

The network layer is responsible for the delivery of individual packets from the source host to the destination host.

Concerned:

Logical addressing (IP Address)

Routing (Source to destination transmission between networks)

TRANSPORT LAYER

The transport layer is responsible for the delivery of a message from one process to another

Concerned:

Service-point addressing (Port address)

Sequence Number (data reassembly)

Segmentation and reassembly (Sequence number)

SESSION LAYER

The session layer is responsible for authentication & authorization.

Concerned:

Session establishment (Starts & terminates sessions)

Dialog Control (allows to communicate 2 systems in Half Duplex/Full duplex)

Synchronization (checks error in fixed time interval to avoid errors)

PRESENTATION LAYER

The presentation layer is responsible for translation, compression and encryption

Concerned:

Translation (interoperability between different encoding system)

Encryption (Privacy schemes)

Compression (data compression)

APPLICATION Layer

The application layer is responsible for providing services to the user.

Concerned:

Web surfing protocols

File transfer, access and management

Mail services

TCP/IP Model

Model

Network Access Layer

• A network layer is the lowest layer of the TCP/IP model.

• A network layer is the combination of the Physical layer and Data Link layer defined in the OSI reference model.

• It defines how the data should be sent physically through the network.

• This layer is mainly responsible for the transmission of the data between two devices on the same network.

• The functions carried out by this layer are encapsulating the IP datagram into frames transmitted by the network and mapping of IP addresses into physical addresses.

• The protocols used by this layer are ethernet & token ring

Internet or Network Layer

• An internet layer is the second layer of the TCP/IP model.

• An internet layer is also known as the network layer.

• The main responsibility of the internet layer is to send the packets from any network, and they arrive at the destination irrespective of the route they take.

• IP Addressing

• Host-to-host communication

• Data Encapsulation and Formatting

• Fragmentation and Reassembly

• Routing

• ARP Protocol

Transport Layer

• The transport layer is responsible for the reliability, flow control, and correction of data which is being sent over the network.

• The two protocols used in the transport layer are User Datagram protocol and Transmission control protocol.

TCP & UDP

Application Layer

• An application layer is the topmost layer in the TCP/IP model.

• It is responsible for handling high-level protocols, issues of representation.

• This layer allows the user to interact with the application.

• When one application layer protocol wants to communicate with another application layer, it forwards its data to the transport layer.

HTTP
SNMP
SMTP
HTTPS
DNS
TELNET
FTP

TCP UDP

TCP vs UDP

TCP UDP Port Numbers of Internet Protocols Suite

ARP & RARP:

Why We Use ARP?

Used to convert an IP address into a physical address such as an Ethernet address.A host wishing to obtain a physical address broadcasting ARP request onto the TCP/IP network.

Why We Use RARP

The Reverse Address Resolution Protocol (RARP) is an obsolete computer networking protocol used by a client computer to request its Internet Protocol (IPv4) address from a computer network.

Reverse Address Resolution Protocol (RARP) is a network layer protocol used to resolve an IP address from a given hardware address (such as an Ethernet address).

CSMA/CA & CSMA/CD

Carrier Sense Multiple Access (CSMA)

This method was developed to decrease the chances of collisions when two or more stations start sending their signals over the datalink layer. Carrier Sense multiple access requires that each station first check the state of the medium before sending.

CSMA/CA

CSMA/CD

Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA)

Carrier Sense Multiple Access/with Collision Avoidance (CSMA/CA) is a network contention protocol used for carrier transmission in networks using the 802.11 standard. In contrast to the Carrier Sense Multiple Access/Collision Detect (CSMA/CD) protocol, which handles transmissions only after a collision has taken place, CSMA/CA works to avoid collisions prior to their occurrence.

CSMA/CA increases network traffic as it requires sending out a signal to the network even before transmitting any real data. This is to listen for any collision scenarios in the network and to inform other devices not to transmit.

Carrier Sense Multiple Access with Collision Detection (CSMA/CD)

Carrier Sense Multiple Access with Collision Detection (CSMA/CD) is a network protocol for carrier transmission that operates in the Medium Access Control (MAC) layer. It senses or listens whether the shared channel for transmission is busy or not, and defers transmissions until the channel is free. The collision detection technology detects collisions by sensing transmissions from other stations. On detection of a collision, the station stops transmitting, sends a jam signal, and then waits for a random time interval before retransmission

PROXY & VPN

PROXY

If you are wanting to surf the web anonymously then proxies can provide you with a means to hide your home IP address from the rest of the world. By connecting to the internet through proxies, the home IP address of your machine will not be shown but rather the IP of the proxy server will be shown.

PROXY SERVER

A proxy server is a server application that acts as an intermediary between a client requesting a resource and the server providing that resource.

What is a VPN ?

A VPN is a service that both encrypts your data and hides your IP address by bouncing your network activity through a secure chain to another server miles away. This obscures your online identity, even on public Wi-Fi networks, so you can browse the internet safely, securely and anonymously.

Remote Access VPN :- A remote access virtual private network (VPN) enables users who are working remotely to securely access and use applications and data that reside in the corporate data center and headquarters, encrypting all traffic the users send and receive.

Intranet VPNs — If a company has one or more remote locations that they wish to join in a single private network, they can create an intranet VPN to connect LAN to LAN.

Extranet VPNs — An extranet VPN links outside customers, suppliers, partners, or communities of interest to an enterprise customer’s network over a shared infrastructure using dedicated connections

Server & Datacenter

What is a Server?

A server is a computer or system that provides resources, data, services, or programs to other computers, known as clients, over a network. In theory, whenever computers share resources with client machines they are considered servers. … This means that a device could be both a server and a client at the same time.

SERVER TYPE

Exchange Server

Microsoft Exchange Server is Microsoft’s email, calendaring, contact, scheduling and collaboration platform. It is deployed on the Windows Server operating system (OS) for business use. Microsoft designed Exchange Server to give users access to the messaging platform from mobile devices, desktops and web-based systems. Telephony capabilities in Exchange Server support voice messages.

Backup Server

A backup server is a type of server that facilitates data, file, application, and/or database backup. It has both hardware and software capabilities so you can manage and recover your backups — it can be locally-based or a remote backup server. … When it comes to cloud deployment, a remote backup server is used.

WHAT IS A DATA CENTER

 Data centers are designed to house information systems and related components such as:

 Servers

 Routers

 Storage

 Uninterruptable power

supplies (UPS)

 Cooling Units

 Data centers have unique and typically large power requirements

 They are often raised floor designs to accommodate the large amount of cables required.

DATA CENTER COMPONENTS: COOLING

 Approximately half of the power consumed in the data center is used in cooling

 Cooling Options

 Computer Room Air Conditioning (CRAC)

 Liquid Cooling

 Air Side Economizers

DATA CENTER COMPONENTS: UPS

Uninterruptable Power Supply (UPS)

Conditions power

Provides power to avoid outages during power failure lasting seconds or minutes

Provides time to sahutdown, failover, or initiate backup power for longer outages

Network Security

Computer Network Security

Computer network security consists of measures taken by business or some organizations to monitor and prevent unauthorized access from the outside attackers.

Privacy :-

The transmitted message should be sent only to the intended receiver while the message should be opaque for others.

Message Integrity :-

Data integrity means that the data must arrive at the receiver exactly as it was sent. There must be no changes in the data content during transmission

Authentication :-

Authentication means that the receiver is sure of the senders identity, i.e., no imposter has sent the message.

Non Repudiation :-

Non-Repudiation means that the receiver must be able to prove that the received message has come from a specific sender.

Encryption/Decryption

Encryption: Encryption means that the sender converts the original information into another form and sends the unintelligible message over the network.

Decryption: Decryption reverses the Encryption process in order to transform the message back to the original form.

The data which is to be encrypted at the sender site is known as plaintext, and the encrypted data is known as ciphertext. The data is decrypted at the receiver site.

There are two types of Encryption/Decryption techniques:

• Privacy with secret key Encryption/Decryption

• Privacy with public key Encryption/Decryption

Algorithms :- DES, 3DES, AES & RCA, RSA

Secret Key Encryption/Decryption technique

In Secret Key Encryption/Decryption technique, the same key is used by both the parties, i.e., the sender and receiver.

Public Key Encryption/Decryption technique

There are two keys in public key encryption: a private key and a public key. The private key is given to the receiver while the public key is provided to the public.

NAS & NAT

Network Attached Storage (NAS)

Network-attached storage (NAS) is dedicated file storage that enables multiple users and heterogeneous client devices to retrieve data from centralized disk capacity. Users on a local area network (LAN) access the shared storage via a standard Ethernet connection.

Network Address Translation (NAT)

To access the Internet, one public IP address is needed, but we can use a private IP address in our private network. The idea of NAT is to allow multiple devices to access the Internet through a single public address. Network Address Translation (NAT) is a process in which one or more local IP address is translated into one or more Global IP address

● Uses private addresses:

■ 10.0.0.0–10.255.255.255,

■ 172.16.0.0–172.32.255.255 or

■ 192.168.0.0–192.168.255.255

Network Address Translation (NAT)

There are 3 ways to configure NAT:

Static NAT :-

A static network address translation (static NAT) is a type of NAT technique that routes and maps network traffic from a static public IP address to an internal private IP address and/or network.

Dynamic NAT :-

Dynamic network address translation (Dynamic NAT) is a technique in which multiple public Internet Protocol (IP) addresses are mapped and used with an internal or private IP address.

Port Address Translation (PAT) :-

Port address translation (PAT) is a function that allows multiple users within a private network to make use of a minimal number of IP addresses. Its basic function is to share a single IP public address between multiple clients who need to use the Internet publicly. It is an extension of network address translation (NAT).

Basic Operation of NAT

RAID (Redundant Array of Independent Disk)

RAID, or “Redundant Arrays of Independent Disks” is a technique which makes use of a combination of multiple disks instead of using a single disk for increased performance, data redundancy or both.

Sharing Folder in Network

For Sharing…

Permissions
Discovery of Network
Sharing Privacy
Firewall Rule
Same Network

Telnet in Network

Telnet Remote Config?

Telnet utility allows users to test connectivity to remote machines and issue commands through the use of a keyboard.

Network Virtual Terminal

Network Virtual terminal: An application layer allows a user to log on to a remote host.

Remote Desktop Connection

Remote Desktop Connection (RDC) is a technology that permits a computer to connect, gain access and take control of a remote PC over a network. It implements Remote Desktop Protocol (RDP) through Terminal service or Windows Remote Desktop Service to gain remote access over a computer or a network.

Windows Remote Assistance

A remote assistance when enabled allows another user on the Internet to use your computer. This may be asked by Microsoft agent or your friend or something else. Take caution while giving anyone remote access, this means everything in the PC is accessible to the one who has taken control.

FTP in Network

FTP (File Transfer Protocol)

A popular means of data exchange is connecting computers to one another. The File Transfer Protocol (FTP) is used to transfer files between two computers over a network and Internet. … Auto FTP Manager is an advanced FTP client that automates file transfers between your computer and the FTP server.