Define Protocol:
Protocol is usually an agreed-upon or standardized method for transmitting data and/or establishing communications between different devices.
What are these Protocol's used for?
- TCP/IP
- http
- smtp
- pop
- FTP
A Family of Protocols
TCP/IP is a large collection of different communication protocols based upon the two original protocols TCP and IP.TCP - Transmission Control Protocol
TCP is used for transmission of data from an application to the network.TCP is responsible for breaking data down into IP packets before they are sent, and for assembling the packets when they arrive.
IP - Internet Protocol
IP takes care of the communication with other computers.IP is responsible for the sending and receiving data packets over the Internet.
HTTP - Hyper Text Transfer Protocol
HTTP takes care of the communication between a web server and a web browser.HTTP is used for sending requests from a web client (a browser) to a web server, returning web content (web pages) from the server back to the client.
HTTPS - Secure HTTP
HTTPS takes care of secure communication between a web server and a web browser.HTTPS typically handles credit card transactions and other sensitive data.
SSL - Secure Sockets Layer
The SSL protocol is used for encryption of data for secure data transmission.SMTP - Simple Mail Transfer Protocol
SMTP is used for transmission of e-mails.MIME - Multi-purpose Internet Mail Extensions
The MIME protocol lets SMTP transmit multimedia files including voice, audio, and binary data across TCP/IP networks.IMAP - Internet Message Access Protocol
IMAP is used for storing and retrieving e-mails.POP - Post Office Protocol
POP is used for downloading e-mails from an e-mail server to a personal computer.FTP - File Transfer Protocol
FTP takes care of transmission of files between computers.NTP - Network Time Protocol
NTP is used to synchronize the time (the clock) between computers.DHCP - Dynamic Host Configuration Protocol
DHCP is used for allocation of dynamic IP addresses to computers in a network.SNMP - Simple Network Management Protocol
SNMP is used for administration of computer networks.LDAP - Lightweight Directory Access Protocol
LDAP is used for collecting information about users and e-mail addresses from the internet.ICMP - Internet Control Message Protocol
ICMP takes care of error-handling in the network.ARP - Address Resolution Protocol
ARP is used by IP to find the hardware address of a computer network card based on the IP address.RARP - Reverse Address Resolution Protocol
RARP is used by IP to find the IP address based on the hardware address of a computer network card.BOOTP - Boot Protocol
BOOTP is used for booting (starting) computers from the network.PPTP - Point to Point Tunneling Protocol
PPTP is used for setting up a connection (tunnel) between private networks.What does GUI stand for?What was used before GUI?
In computer lingo, the letters “GUI” stand for graphical user interface. Basically this means that when you point your mouse or cursor to a particular icon and click on it, a hidden list of commands is automatically created for your computer to follow. GUI has replaced the need to enter DOS commands. Before GUI, PUI (PARC User Interface) was in use.
There are two methods of data transmission – serial and parallel. Explain the difference between them.
Digital data transmission can occur in two basic modes: serial or parallel. Data within a computer system is transmitted via parallel mode on buses with the width of the parallel bus matched to the word size of the computer system. Data between computer systems is usually transmitted in bit serial mode . Consequently, it is necessary to make a parallel-to-serial conversion at a computer interface when sending data from a computer system into a network and a serial-to-parallel conversion at a computer interface when receiving information from a network. The type of transmission mode used may also depend upon distance and required data rate.
Parallel Transmission
In parallel transmission, multiple bits (usually 8 bits or a byte/character) are sent simultaneously on different channels (wires, frequency channels) within the same cable, or radio path, and synchronized to a clock. Parallel devices have a wider data bus than serial devices and can therefore transfer data in words of one or more bytes at a time. As a result, there is a speedup in parallel transmission bit rate over serial transmission bit rate. However, this speedup is a tradeoff versus cost since multiple wires cost more than a single wire, and as a parallel cable gets longer, the synchronization timing between multiple channels becomes more sensitive to distance. The timing for parallel transmission is provided by a constant clocking signal sent over a separate wire within the parallel cable; thus parallel transmission is considered synchronous .Serial Transmission
In serial transmission, bits are sent sequentially on the same channel (wire) which reduces costs for wire but also slows the speed of transmission. Also, for serial transmission, some overhead time is needed since bits must be assembled and sent as a unit and then disassembled at the receiver.Serial transmission can be either synchronous or asynchronous . In synchronous transmission, groups of bits are combined into frames and frames are sent continuously with or without data to be transmitted. In asynchronous transmission, groups of bits are sent as independent units with start/stop flags and no data link synchronization, to allow for arbitrary size gaps between frames. However, start/stop bits maintain physical bit level synchronization once detected.
Applications
Serial transmission is between two computers or from a computer to an external device located some distance away. Parallel transmission either takes place within a computer system (on a computer bus) or to an external device located a close distance away.A special computer chip known as a universal asynchronous receiver transmitter (UART) acts as the interface between the parallel transmission of the computer bus and the serial transmission of the serial port. UARTs differ in performance capabilities based on the amount of on-chip memory they possess.
Examples
Examples of parallel mode transmission include connections between a computer and a printer (parallel printer port and cable). Most printers are within 6 meters or 20 feet of the transmitting computer and the slight cost for extra wires is offset by the added speed gained through parallel transmission of data.Examples of serial mode transmission include connections between a computer and a modem using the RS-232 protocol . Although an RS-232 cable can theoretically accommodate 25 wires, all but two of these wires are for overhead control signaling and not data transmission; the two data wires perform simple serial transmission in either direction. In this case, a computer may not be close to a modem, making the cost of parallel transmission prohibitive-thus speed of transmission may be considered less important than the economical advantage of serial transmission.
Define the term “URL”.Explain the components that
make up the url.
Abbreviation of Uniform Resource Locator (URL) it is the global address of documents and other resources on the World Wide Web.The first part of the URL is called a protocol identifier and it indicates what protocol to use, and the second part is called a resource name and it specifies the IP address or the domain name where the resource is located. The protocol identifier and the resource name are separated by a colon and two forward slashes.A URL for HTTP (or HTTPS) is normally made up of three or four components: - A scheme. The scheme identifies the protocol to be used to access the resource on the Internet. It can be HTTP (without SSL) or HTTPS (with SSL).
- A host. The host name identifies the host that holds the resource. For example, www.example.com. A server provides services in the name of the host, but there is not a one-to-one mapping between hosts and servers. Host names explains more about host names.Host names can also be followed by a port number. Port numbers explains more about these. Well-known port numbers for a service are normally omitted from the URL. Most servers use the well-known port numbers for HTTP and HTTPS , so most HTTP URLs omit the port number.
- A path. The path identifies the specific resource within the host that the Web client wants to access. For example, /software/htp/cics/index.html.
- A query string. If a query string is used, it follows the path component, and provides a string of information that the resource can use for some purpose (for example, as parameters for a search or as data to be processed). The query string is usually a string of name and value pairs, for example, q=bluebird.
In the context of data
transmission, what is “error detection”?
In communications, error detection refers to a class of techniques for detecting garbled messages. Two of the simplest and most common techniques are called checksum and CRC. More sophisticated strategies include MNP and CCITT V.42 .
Why would error detection be
important for the internet?
Error Detection is important because the receiver detects an error, it can be
corrected, or it can simply be reported.
Name and explain one common
method of error detection.
Parity Method for Error Detection
The movement of digital data from one
location to another can result in transmission errors, the receiver not
receiving the same signal as transmitted by the transmitter as a result of
electrical noise in the transmission process. Sometimes a noise pulse may be
large enough to alter the logic level of the signal. For example, the
transmitted sequence 1001 may be incorrectly received as 1101. In order to
detect such errors a parity bit is often used. A parity bit is an extra 0
or 1 bit attached to a code group at transmission. In the even parity
method the value of the bit is chosen so that the total number of 1s in the code
group, including the parity bit, is an even number. For example, in transmitting
1001 the parity bit used would be 0 to give 01001, and thus an even number of
1s. In transmitting 1101 the parity bit used would be 1 to give 11101, and thus
an even number of 1s. With odd parity the parity bit is chosen so that
the total number of 1s, including the parity bit, is odd. Thus if at the
receiver the number of 1s in a code group does not give the required parity, the
receiver will know that there is an error and can request that the code group be
retransmitted.
An extension of the parity check is the
checksum in which a block of code may be checked by sending a series of
bits representing their binary sum. Parity and checksums can only detect single
errors in blocks of code, double errors go undetected. Also, the error is not
located so that correction by the receiver can be made. Multiple-error detection
techniques and methods to pinpoint errors have been devised (See Section 21.3 of
Bolton) and texts such as Audio, Video, and Data Telecommunications by D.
Peterson (McGraw-Hill 1992) explain these in more detail.
What is HTML and explain why it
is important?
HyperText Markup Language (HTML) is the main markup language for web pages. HTML elements are the basic building-blocks of webpages. It is important because it helps create webpages.
Some excellent posting!! Many topics and very thorough.
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Thankyou Sir :D
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