computer networking

✅ Protocols: Protocols are set of rule that are define by internet society.

✅ TCP(Transmission Control Protocol): It will ensure that the data will reach its destination and it will not be like corrupted.(means 100% data will be transfer)

✅ UDP(User Datagram Protocol): Used for communication throught the internet,It is specifically chosen for time-sensitive application like gaming,playing video.(means 100% data will not be reach)

✅ HTTP(Hypertext Transfer Protocol): It was design for communication between web browser and web server.

✅ HTTPS(Hypertext Transfer Protocol Secure): It was design for communication between web browser and web server. Data sent using HTTPS is secured via transport layer security protocol,which provide three key layer of protection.

✅ Packet: A network packer is small amount of data sent over transmission control protocol and internet protocol(TCP/IP) network.

✅ IP Address(Internet Protocol):Ip address are used to identify hardware devices on a network.The addresses allow these devices to connect to one another and transfered data on local network or over the internet.

✅ Modem: Modem is a computer hardware device that convert data from a digital format into a format suitable for an analog transmission medium such as telephone and redio.

✅ Router: A router is a device that is used for forwarding the internet connection to all the connected devices.

Note: All the devices that is connected to the modem and router have same ip address.

✅ Dynamic Host Configuration Protocol: Is a network management protocol used an internet protocol networks for automatically assigning IP addresses.

✅ Network Address Translation: Is a process that enables one unique ip address to represent entire group of computer.

✅ Open System Interconnection Model: The OSI model(Open Systems Interconnection Model) is a conceptional framework used to describe the function of a networking system.

✅ Application Layer: An application layer is an abstraction layer that specifies communication protocols and interface methods used by hosts in a communication network.

✅ Function of Application Layer:

✅ It allow users to log on a remote host.
✅ Application layer provides a facility by which users can forward several
emails and it also provide a storage facility.
✅ This layer allows users to access,retrieve,and manage files in a
remote computer.

✅ Presentation Layer : The presentation layer ensures that the communication that pass through it are in the appropriate form for the recipient application.

✅ Function of presentation layer:

✅ It is responsible for data encryption and decryption of sensitive data before they are transmitted over common channels.

✅ Session layer: Session layer is the layer of the open system interconnection model that control the dialogues(connections) between computer. It establishes,manages and terminates the connection between the local and remote application.

✅ Transport Layer: Transport layer provides transparent transfer of data between end users,providing reliable data transfer services to the upper layer.The transport layer controls the reliability of a given link through flow control,segmentation and desegmentation and error control.

✅ Function of transport layer:

✅ Data that is received from session layer it wiil be divided into small data unit called segment,the every segment will contain the source and destination port number and a sequence number basically help you to reassemble segment in the correct order.

✅ Network Layer: The network layer uses network addresses(typically internet protocol address) to route packet to a destination node.

✅ Function of network layer:

✅ The primary function of the network layer is to enable different networks to be interconnected.
✅ It does this by forwarding packets to network routers.

✅ Data link layer: The data link layer will receive the data packet from the network layer and this data packet contains the ip address of sender and receiver. It is responsible for node to node delivery of data.

✅ Physical Layer: The physical layer defines the relationship between a device and a transmission medium such as a copper or optical cable.This include the layout of pins,voltage,network adapter,host bus adapter.

• ✅ Sockets: A socket is one endpoint of a two-way communication link between two program running on the network. socket are commonly used for client and server interaction.

  ✅ Ephemeral port: An ephemeral port is a temporary communication hub used for internet protocol communication.

  ✅ Cookies: Cookies are text files with small piece of data like username and password that are used to identify your computer as you use computer network.specifies cookies know as HTTP cookies are used to identify specific users and improve web browsing experience.

  ✅ How Email Works ?

  ✅ SMTP(Simple Mail Transfer Protocol): These protocols are important for sending and distributing outgoing emails.This protocol uses the header of the mail to get the email id of the receiver and enter the mail into the queue of outgoing mails.

  ✅ POP3(Post Office Protocol3): Is the most commonly used protocol for receiving email over the internet.

  ✅ IMAP(Internet Message Access Protocol): IMAP allows you to accesss your email wherever you are from any device.

  ✅ DNS(Domain Name System):Is a hierarchical naming system built on a distributed database for computers,services or any resources connected to the internet or a private networks.

  ✅ Function of Domain Name System: DNS translate domain names to IP addresses so browsers can load internet resource.

  ✅ If you want to search url then how they work internally:

  ✅ It will check in own computer.

  ✅ Basically what happend when you visit website for the first time,it will stored value of its ip address that it has found in your local device.

  ✅ If its not find in local device then it will search in local DNS server(Internet Service Provider).

  ✅ If its not found in Internet service provider then it check in root server.

  ✅ If its not found in root server then it will check in top level domain.

  ✅ Top level domain have all the information they will give the ip address of that url,then this will connect to be your url.