Cyclic Redundancy Check(CRC) is a common technique for detecting data transmission errors. It’s a type of hash function which is used to produce a checksum a small, fixed number of bits against a block of data, such as a packet of network traffic or a block of a computer file. The checksum is used to detect errors after transmission or storage. Transmitted messages are divided into predetermined lengths that are divided by a fixed divisor.

According to the calculation, the remainder number is attached onto and sent with the message. When the message is received, the computer recalculates the remainder and compares it to the transmitted part to confirm that no changes occurred on transit. If the numbers do not match, an error is detected.

CRC checks happen every time you read the media. Many CD and DVD burning programs will include a read pass immediately after writing, to ensure that the data was written properly.

CRCs are popular because they are simple to implement in binary hardware, easy to analyze mathematically, and are particularly good at detecting common errors caused by noise in transmission channels.

A number of file transfer protocols, including Zmodem, use CRC in addition to checksum.

Peer-to-peer network is a communications network that allows all computers in the network to act as servers and share their files with all other users on the network. On the Internet, peer-to-peer network is a type of transient Internet network that allows a group of computer users with the same networking program to connect with each other and directly access files from one another’s hard drives. Peer to Peer networks also referred to as P2P networks are generally used for connecting nodes via largely distinct connections. Such networks are useful for many purposes like sharing content files containing audio, video, data or anything in digital format is very common, and realtime data, such as telephony traffic, is also passed using P2P technology.

A Terminal Adapter is an electronic device that interfaces a computer to an external digital communications line, such as an Integrated Services Digital Network (ISDN) phone line. A terminal adapter is a bit like a modem and often referred to as modem but because it is digital, a terminal adapter is not exactly a modem, A modem needs to convert between analog and digital signals, on the other hand, a terminal adapter only needs to pass along digital signals. As ISDN becomes more common, future computers might probably have terminal adapters built in. As of now you need to purchase a separate terminal adapter if you want ISDN access. You can get an internal adapter or an external adapter than connects to your computer’s serial port.

Packet-

A packet refers to the unit of data that is in passage between an origin and a destination on the Internet or any other packet-switched network. Every page that you receive on the Internet comes as a series of packets, and every e-mail you send leaves as a series of packets. Networks that ship data around in small packets are called packet switched networks. The TCP/IP protocol breaks large data files into smaller “packets” for swift transmission over the Internet. When the data reaches its destination, the protocol makes sure that all packets arrived without error. A typical packet contains perhaps 1,000 or 1,500 bytes. Packets are also referred to by other names like frame, block, cell or segment depending on the type of network.

Packet Switching-

Packet Switching refers to the method of moving data around the Internet that allows many people to use the same lines at the same time. In packet switching, all data being transferred from a source is divided into packets, with each packet bearing the address of its origin and destination. This enables packets from different sources to be simultaneously transferred, sorted and directed on the same line. Each packet is then transmitted individually and can even follow different routes to its destination. Once all the packets forming a message arrive at the destination they are reassembled into the original message. ,A packet-switching scheme is an efficient way to handle transmissions on a connectionless network such as the Internet

With relation to computer technology, “on the fly” describes activities that develop or occur dynamically rather than as the result of something that is statically predefined. For instance, the page content sent to the user from a Web site can be developed on it on the basis of dynamic factors such as hours of a day, the time and date can be seen.The Web server mainly calls an application program to produce the “on-the-fly” page that is to be given back. But there are several techniques for on-the-fly page development which include the use of cookies, the server side which include Microsoft’s Active Server Pages, and PHP. A page created on the fly may have its own URL but this is not necessary which contains all data on which the page depends upon.

Hypertext Transfer Protocol (http) is a system for transmitting and receiving information across the Internet. Http serves as a request and response procedure that all agents on the Internet follow so that information can be rapidly, easily, and accurately disseminated between servers, which hold information, and clients, who are trying to access it. Http is commonly used to access html pages, but other resources can be utilized as well through http. While exchanging confidential information with a server, which needs to be secured in order to prevent unauthorized access a client needs some sort of security which is provided by https, or secure http which allows authorization and secured transactions.

If you visit a website or webpage, and look at the address in the web browser, it will most likely begin with the following: http://. This means that the website is connected to your browser using the regular unsecure language, due to which there is a possiblilty for someone to spy on your computer’s conversation with the website. If you fill out a form on the website, someone might see the information you send to that site.

But if the web address begins with https://, that basically means your computer is talking to the website in a secure code that no one can spy on the information you fill in.

https is quite similar to http, because it follows the same basic protocols. The http or https client, such as a Web browser, establishes a connection to a server on a standard port. When a server receives a request, it returns a status and a message, which may contain the requested information or indicate an error if part of the process malfunctioned. Both systems use the same Uniform Resource Identifier (URI) scheme, so that resources can be universally identified. Use of https in a URI scheme rather than http indicates that an encrypted connection is desired.

When using an https connection, the server responds to the initial connection by offering a list of encryption methods it supports. In response, the client selects a connection method, and the client and server exchange certificates to authenticate their identities. After this is done, both parties exchange the encrypted information after ensuring that both are using the same key, and the connection is closed. In order to host https connections, a server must have a public key certificate, which embeds key information with a verification of the key owner’s identity. Most certificates are verified by a third party so that clients are assured that the key is secure.

Https is used in many situations, such as log-in pages for banking, forms, corporate log ons, and other applications in which data needs to be secure. However, if not implemented properly, https is not infallible, and therefore it is extremely important for end users to be wary about accepting questionable certificates and cautious with their personal information while using the Internet.