Introduction to Internet, Domain Name System
- 2. Definition of Internet Definition of Internet • The Internet is not synonymous with World Wide Web. • The Internet is a massive network of networks, a networking infrastructure. • It connects millions of computers together globally, forming a network in which any computer can communicate with any other computer as long as they are both connected to the Internet. • Internet is a world wide public network of computers on which people can join and use
- 3. Advantages Internet covers almost every aspect of life, one can think of. Here, we will discuss some of the advantages of Internet:
- 4. • Internet allows us to communicate with the people sitting at remote locations. • There are various apps available on the web that uses Internet as a medium for communication. One can find various social networking sites such as: • Facebook • Twitter • Yahoo
- 5. • One can surf for any kind of information over the internet. Information regarding various topics such as Technology, Health & Science, Social Studies, Geographical Information, Information Technology, Products etc can be surfed with help of a search engine. • Apart from communication and source of information, internet also serves a medium for entertainment. Following are the various modes for entertainment over internet. • Online Television • Online Games • Songs • Videos
- 6. Disadvantages • However, Internet has proved to be a powerful source of information in almost every field, yet there exists many disadvantages discussed below:
- 7. • There are always chances to loose personal information such as name, address, credit card number. Therefore, one should be very careful while sharing such information. One should use credit cards only through authenticated sites. • Another disadvantage is the Spamming. Spamming corresponds to the unwanted e-mails in bulk. • These e-mails serve no purpose and lead to obstruction of entire system. • Virus can easily be spread to the computers connected to internet. Such virus attacks may cause your system to crash or your important data may get deleted.
- 8. Domain Name System • DNS stands for “Domain Name System”. It’s a system that lets you connect to websites by matching human-readable domain names (like google.com) with the unique ID of the server where a website is stored. • The Domain Name System (DNS) is a hierarchical and decentralized system that translates human-readable domain names into IP addresses, which are used to locate and identify computer systems on the Internet.
- 9. How does DNS work • The internet is a massive network of computers. Each device connected to the internet is assigned a unique IP address which helps other computers identify it. • This IP address is a string of numbers with periods that looks like this: 192.124.249.166 • Now imagine if you had to remember such long strings of numbers to visit your favorite websites. They are hard to remember and don’t tell you anything about the website you’ll see if you enter them in a browser.
- 11. Domain Names • Domain Name is a symbolic string associated with an IP address. • There are several domain names available; some of them are generic such as com, edu, gov, net etc, while some country level domain names such us, uk, au, in,ca ru, etc. • The following table shows the Generic Top-Level Domain names: Domain Name Meaning Com Commercial business Edu Education Gov U.S. government agency Int International entity Mil U.S. military Net Networking organization Org Non profit organization
- 12. • The following table shows the Country top-level domain names:
- 13. Intranet and URL Intranet • Intranet is defined as private network of computers within an organization with its own server and firewall. Moreover we can define Intranet as: • Intranet is system in which multiple PCs are networked to be connected to each other. PCs in intranet are not available to the world outside of the intranet. • Usually each company or organization has their own Intranet network and members/employees of that company can access the computers in their intranet.
- 14. Extranet Extranet • Extranet refers to network within an organization, using internet to connect to the outsiders in controlled manner. • It helps to connect businesses with their customers and suppliers and therefore allows working in a collaborative manner. • It is the type of network that allows users from outside to access the Intranet of an organization.
- 15. Uniform Resource Locator(URL) • Uniform Resource Locator (URL) refers to a web address which uniquely identifies a document over the internet. • A Uniform Resource Locator (URL) is an address that indicates the location of a specific file or resource on the World Wide Web (WWW). • A URL specifies the site of a target saved on a local or networked computer. A file, directory, HTML page, image, application, and more can all be the target. • This document can be a web page, image, audio, video or anything else present on the web. There are two forms of URL as listed below: o Absolute URL o Relative URL
- 17. Difference between absolute and relative URL
Editor's Notes
- #2: For this reason, Berners-Lee is widely regarded as the father of the world wide web (www).
- #9: The Domain Name System (DNS) is a hierarchical and decentralized system that translates human-readable domain names into IP addresses, which are used to locate and identify computer systems on the Internet. In simpler terms, DNS serves as a directory that maps easily memorable domain names (like www.example.com) to their corresponding numerical IP addresses (like 192.168.1.1). Key components and functions of the Domain Name System include: Domain Names: These are human-readable names that individuals use to identify websites and other resources on the Internet. For example, "www.google.com" is a domain name. IP Addresses: Every device connected to the Internet is assigned a unique numerical identifier called an IP address. DNS translates domain names into IP addresses, allowing computers to communicate with each other. DNS Servers: The DNS system is distributed across a network of servers worldwide. DNS servers store and manage databases of domain names and their corresponding IP addresses. There are different types of DNS servers, including authoritative DNS servers, recursive DNS servers, and caching DNS servers. Hierarchy: DNS follows a hierarchical structure. The domain name space is divided into levels, with the top-level domain (TLD) at the highest level (e.g., ".com," ".org," ".net"). Below the TLD, there are second-level domains (SLD), and subdomains can be further nested.
- #11: International Telecommunication Union (ITU) – example for .int Org > non-profit organization, charities, open source projects and communities
- #14: Suppliers can log in to the extranet to view purchase orders, track shipments, and update delivery statuses.Inventory Management: Suppliers can access real-time inventory levels of products they supply to XYZ Stores, allowing them to anticipate restocking needs and plan their production schedules accordingly.
- #15: A URL (Uniform Resource Locator) consists of several components, each serving a specific purpose. Let's break down the URL http://www.google.com: Scheme/Protocol: http:// This specifies the protocol used to access the resource. In this case, it's HTTP (HyperText Transfer Protocol), which is used for transferring web pages over the internet. Another common protocol is HTTPS (https://), which is the secure version of HTTP. Subdomain: www This is the subdomain, which is a part of the domain name. The www stands for World Wide Web. Subdomains can be used to organize different sections of a website. For example, blog.example.com or shop.example.com are subdomains of example.com. Domain Name: google This is the main part of the URL that identifies the website. It is typically chosen by the website owner and registered through a domain name registrar. Top-Level Domain (TLD): .com This is the extension of the domain name, indicating the type of organization or geographical location. Common TLDs include .com (commercial), .org (organization), .net (network), and country-specific TLDs like .uk (United Kingdom) or .ca (Canada). Putting these parts together: http:// (scheme) www (subdomain) google (domain name) .com (TLD)
- #17: Absolute URL: Used to link web pages on different websites: Absolute URLs provide a complete address, including the protocol (like “http” or “https”), domain name, and path. They are used when linking to external resources or pages on other websites. Difficult to manage: Managing absolute URLs can be challenging because any changes to the domain or directory structure require updating all references. Changes when the server name or directory name changes: If the server name or directory structure changes, absolute URLs need to be updated accordingly. Take time to access: Retrieving content via absolute URLs involves additional DNS lookups and can be slower. Relative URL: Used to link web pages within the same website: Relative URLs are shorter and only specify the path relative to the current page. They are ideal for internal links within a website. Easy to manage: Since relative URLs don’t include the full domain, they are easier to maintain when site structure changes. Remains the same even if we change the server name or directory name: Relative URLs adapt automatically to changes in the site’s structure. Comparatively faster to access: Retrieving content via relative URLs is quicker because it avoids additional DNS lookups.