Fundamental of Programming

 Application layer Provides protocols that allow software to send and receive information and present meaningful data to users. Used by end-user software. Examples: Hypertext Transfer Protocol (HTTP), File Transfer Protocol (FTP), Domain Name System (DNS), Simple Mail Transfer Protocol (SMTP), and Post Office Protocol (POP). Hypertext Transfer Protocol (HTTP): Data protocol used in World Wide Web (Communication between web clients and servers). Communication between client computers and web servers is done by HTTP requests and receiving HTTP responses. Hypertext Transfer protocol Secure (https) is a combination of Hypertext Transfer Protocol (HTTP) with the Secure Socket Layer (SSL)/ Transport Layer Security (TLS) (authentication and security protocol). File Transfer Protocol (FTP): Refers to a group of rules that govern how computers transfer files one system to another over the internet. FTP uses three different modes: block, stream, and compressed. Stream Mode:  It is the d...

 Layering: Divides a task into sub-tasks and then solve each sub-task independently. Advantages of layering: Extensibility. Facilitates modular engineering. Accelerates evolution. Simplifies teaching and learning. OSI Model (Open System Interconnection Reference Model): It is a description for layered communications and computer network protocol and transmission design. It is also referred to as OSI Seven Layer Model. Layers and its functions: 1. Application: Gives access to network resources.                                      Protocols: SMTP, HTTP, FTP. 2. Presentation: Translates, encrypts and compresses data.                            Protocol: MPEG, ASCH, SSL. 3. Session: Ensures establishment and termination of the session.                    Protocol: NetBIOS, ...

 Introduction to Network Devices Repeater: Operates at the physical layer. Its job is to regenerate signal over the same network before the signal becomes too weak or corrupted. Hub: It is a multiport repeater. It connects multiple wires coming from different branches. Cannot filter data. They do not have the intelligence to find out the best path for data packets which leads to inefficiencies and wastage. Types of Hubs: 1.Active Hub: Hubs that have their own power supply and can clean, boost, and relay the signal along with the network. Serves both as a repeater as well as a wiring center. Used to extend the maximum distance between nodes. 2. Passive Hub: Hubs that collect wiring from nodes and power supply from the active hub. Relay signals onto the network without cleaning and boosting them. Can't use to be extend the distance between nodes. 3. Intelligent Hub: Works like active hubs and includes remote management capabilities. Provide flexible data rates to the network devices....

 Network communication 1kb/s = 1000 bits per second  1KB/s= 1021 bytes per second  File size is always measured in kilo Bytes and download speeds are always calculated based on how many bytes per second are downloaded and hence kilobytes and kilobits are interchangeable. (512 kbps can never achieve a download speed of 512 KBps) Components of networks Network interface card (NIC):  a hardware component which is installed on a computer so it can connect to a network. Network medium: A cable that plugs into the NIC and makes the connection between a computer and the rest of the network. Interconnecting device: allows two or more computers to communicate on the network without having to be connected directly to one another. Software components Network client software: Requests information stored on another network computer or device. Network server software: Allows a computer to share its resources. Protocols: Defines the rules a computer uses when sending information ac...