Domain Names

The dotted decimal notation system was difficult to remember, & hence a new IP addressing system using words was evolved. In this system, an address such as www.amazon.com is called a domain name. Domain names are sets of words that are assigned to specific IP addresses, & these names can have two or more word groups separated by periods. Domain names are formed by the rules and procedures of 'domain name system'. The extreme right part of the domain name is the most general, & each part of it becomes more specific as we move to the left from right. As an example, the domain name www.amazon.com contains 3 parts separated by periods. Starting at the right, the name 'com' indicates that the computer belongs to a company, the company is identified by the name 'amazon', & the word 'www' indicates that the computer is running software that makes it a part of the 'World Wide Web'. 
Domain names are organized in subdomains or subordinate levels of DNS root domain, which is nameless. The rightmost part of the domain name is called a "top level domain",which include generic top level domains, such as com, edu, gov, net, info, mill, biz, name, pro, int, & org and the country code top level domains, such as uk, us, ca, au, & de. The Internet Corporation for Assigned Names & Numbers (ICANN) is responsible for managing domain names, & coordinating with the IP address registrars.


Fundamentals of IP Address

IP Address:

This is a numerical label assigned to each device participating in a computer network that uses Internet Protocol for communication. The functions of IP address are to identify the host or network interface, & location address.

Internet Protocol Version 4: (Standard: RFC 791)

This protocol uses a 32 bit number to identify computers connected to the internet. Computers do all the internal calculations using a binary number system in which each digit is either a 0 or a 1, corresponding to a state of either OFF or ON.  IP Version 4 allows more than 4 billion different addresses, as 2³² = 4, 294,967,296. When a router breaks a message into packets before sending it onto the internet, the router marks each packet with both the source & destination IP addresses of the message. Each IP address appears as 4 numbers separated by periods specified under the dotted decimal notation system, & each of the 4 numbers is an 8 bit number. In networking applications, an 8 bit number is called an octet, & in binary, an octet can have values from 00000000 to 11111111, & the decimal equivalents of these binary numbers are 0 and 255 respectively. As each of the 4 parts of a dotted decimal number can range from 0 to 255, IP addresses range from (32 zeros in binary) to (32 ones in binary).


Introduction to Networks

Internet uses packet switching technology to move data between two points. On a packet-switched network, files and email messages are broken down into small pieces or packets, that are electronically labeled with their origins, sequences, & destination addresses. Packets travel from one computer to another along the interconnected networks untill they reach their destinations. Each packet can take a different path through the interconnected networks, & the packets may arrive out of order. The destination computer collects the packets & reassembles the original file or email message from the pieces in each packet.
Routers: When an individual packet travels from one network to another, the computers through which the packet travels determine the best possible route for getting the packet to its destination. The computers that decide how best to forward each packet are called routers or gateway computers.  The programs on routers that determine the best possible path on which to send each packet are called routing algorithms.The routing algorithms use the information they have stored in routing tables. This information includes (1)list of connections that lead to particular groups of other routers, (2)rules that specify which connections to use first, & (3)rules for handling instances of heavy packet traffic and network congestion.


Review: Internet Encryption

The program that transforms normal text, called plain text, into cipher text (the unintelligible string of characters) is called an encryption program. It is the process of encoding data in such a way that only authorized users can read it. Here the data or information is encrypted using an encryption algorithm, making it an unreadable ciphertext. The process is usually accomplished with the use of an encryption key, which specifies the modus operandi of the data encoding. The authorized users can decode the ciphertext using decryption algorithm, which requires a secret decryption key. There are two types keys used in present encryption system.
Private Key: Here the encryption and decryption keys are the same. The communicating users must agree on a secret key before starting communication. It can be difficult to distribute new keys to authorized users in each transaction, while maintaining security and control over the keys. The main disadvantage of private keys is that they do not scale well in very large environments such as the internet. Here, x individual internet clients would require (x(x-1))/2 private key pairs.
Public Key: This is a latest technological development, & here the key is meant for anyone to use and encrypt the data/message. However, the receiving user has access to the decryption key, & is capable of reading the encrypted data. Symantec Corporation's 'Pretty Good Privacy (PGP)' is a data encryption & decryption algorithm, & is very often used for signing, encrypting, & decrypting texts, emails, files, directories, & whole disk partitions to increase the security of email communications. PGP follows OpenPGP standard RFC 4880 for data encryption & decryption.


Product Review: Amazon's Top Watch


Expensive collectible watches, valued for their incredible feat of expert engineering workmanship and aesthetic appeal, often have mechanical movements powered by springs, & provide additional features such as timers, altimeter, moon phase, slide rule bezel, chronographs, GPS technology, & heat-rate monitoring capabilities that work in tandem in addition to simple time keeping. While shopping a watch, whatever the price or style, the brand name can play an important role in determining the right watch. Brand choice can be highly subjective, & will vary from person to person. Finally it comes down to how you perceive a brand, & what it represents, as well as what it speaks to your sensibilities - high style or horological history, modern or traditional, collectible or affordable.
Automatic or mechanical watches are made up of 130 or more parts that work in tandem to tell the time, & these timepieces have no batteries. Automatic movements mark the passage of time by a series of gear mechanisms, & are wound by the movement of your wrist as you wear it. Self-winding (automatic) watches utilize kinetic energy, the swinging of your arm, to provide energy to an oscillating rotor to keep the watch ticking. If you do not wear the watch consistently, for about 8-10 hours a day, you can keep the watch powered with a watch winder. Always refer the Owner's Manual.