Internet Educational Tips
Friday, April 11, 2008
How TCP/IP Works?
Data sent across the internet is broken up into packets of less than about 1500 characters each. Each packet is given a “header” which holds the information needed to put the packets back in right order again. To each header is adder a “checksum” basically a number that checks whether the precise amount of data in the packet has been received or not. Each packet is put into what is called an IP “envelope” a packet of data with a common address and other specifications. Once the packets go through the routers to their destination, TCP at the receiver’s end, calculates a checksum for each packet and then packet and then compares it with the checksum that was sent in the packet. If these don’t match, the computer figures that the data has been corrupted en route, discards the packet, and requests the sender to resend the packet. TCP then assembles them into their original coherent form to allow the receiving computer to make sense of it.
None of would possible, however , without a DNS server acting as mediator.
Labels: Internet Tips, TCP/IP
Thursday, April 10, 2008
TCP/IP
The current protocol is called IPv4. Each IP address is actually just four number each ranging from 0 to 255 (each of which is called an “octet”) and separated by decimal points (called dots). IP addresses are, therefore in the format xxx.xxx.xxx.xxx where each xxx could be any number from 0 to 225. So an IP address could look something like 161.184.138.36. This address is essential during every exchange of data on the Internet, because it identifies the client computer (which makes the request, and to which the data must be sent) and the destination can happen on the Internet unless your computer is first assigned an IP address.
Say you have specified the IP address of a Web site you wish to access. A server usually has a static IP address. However, your home PC, if you are connecting to the Internet through a modem, is usually assigned a different IP address by the ISP each time you dial in. This IP address is unique to you as a user, but only for as long as the session lasts. The reason for this system is that ISPs have to deal with a large number of requests at the same time. Besides, at any given time, the number of users of the ISP server is limited. To assign permanent IP address to retail users wouldn’t really be required; instead, ISPs simply allot any IP address that is not being used at the time to each user who has just dialed in. This system enables the ISP to get along with fewer IP addresses for the number of users who are connected simultaneously.TCP breaks down and reassembles packets of data. IP ensures that the packets are sent to the right destination. The TCP/IP combination is used because the Internet is a “packet-switched” network. In a circuit- switched network, in contrast, once a connection is made, that specific part of the network is exclusively used only for that connection. “In a packed-switched network”. The connection between sender and the receiver is not single and unbroken. When information is sent, it is broken into small packets and sent over many different routes at the same time and then put together in order at the other end once the pockets of data reach the destination.
Labels: IP Address, TCP/IP
