Internet Service Providers and Domain Name Servers

    Hello guys in this post we learn about Internet service providers and Domain name servers. I hope you like this post so lets continue.

Internet Service Provider :-

• An Internet Service Providers (ISP) or Internet Access providers (IAP) is a company providing access to Internet and host data.
• With advent of Internet and its increasing demand it was necessary to provide internet access and hosting facilities for personal as well as commercial use. 
• To meet this ever increasing demand, commercial ISPs come into existence in 1990.
• this companies provide the necessary infrastructure using coaxial cables, fibers optic cables or wireless connection and allow the customers to access Internet. ISPs also provides space to host small business.
• ISPs facilitating internet connections through phone lines such as dial-up do not require the physical address of the user.
• But ISPs using cable or any other lines to provide access require registration of the user with ISP.
• ISP host facilities e-mail, FTP and web hosting services. other services of ISP host may include Virtual Machines, clouds or software server facilities.
• ISPs may take service from upstream ISPs and work in hierarchy. They categorized as:     

             1) Peering : These ISPs may connect to each other through peering points or internet exchange points for controlling networks server traffic and data exchange.

             2) Virtual ISP (VISP) : Thes ISPs purchase services from one ISP and lend it to the end user so as to reduce set up cost on the end users  side.

              3)Free ISP : These are known as free nets as they run on no profit basis to offer free of cost services to the users.

• Facilities provided by ISPs for individual users and small business users include:

1. Dial-up connections
2. DSL (Digital Subscriber lines)
3. Broadband Wireless connections 
4. Modem
5. Coaxial and fiber optic connections

• The facilities offered for large business include :

1. DSL (Digital Subscriber lines)
2. Ethernet 
3. Gigabyte, Metro or satellite Ethernet
4. Frame relay

Domain Name Server :-

• Domain Name System is a hierarchical naming system used for connecting to Internet or to any private network.

• This system mainly translates unique numeric string corresponding to resources or domain or identifying devices on the network to meaningful network domain names which are easy to remember.

• Domain Name System enables to give unique names to group of networks or domains irrespective of where they are located.

• Domain Name System uses nodes called Domain Name Servers for allocating and mapping the unique numeric IP addresses to Domain names.

• Each domain has minimum one DNS server also known as authoritative DNS that publishes the information about the domain.

• The top of the hierarchy acts as root name server which the subordinate servers query when resolving a Top Level Domain. The Top Level domain requires a primary DNS and one or more secondary DNS.

• The DNS query starts with recursive queries at the root. DNS resolver at the client-side of the Domain Name Server iterates through various name servers to seek necessary information like translating a domain name into the IP address of the host sought.

   1. Internet Address

• Internet Address helps to identify a node on the network. It is also known as IP address as it follows TCP/IP suite.

• IP is a numeric string that uniquely identifies a computer system or device on the network and location addressing.

• Internet Protocol or IP address was initially defined as a 32-bit number and was known as IPv4 i.e. Internet Protocol version 4 also used today.
• As the use of Internet increased the available IP addresses were exhausted and a new addressing system, IPv6 was developed in 1995 which uses 128 bits for address.
• IPv4 address is represented as a 32-bit integer in dot-decimal notation represented in 4 octets of address expresses as decimal numbers ranging from 0 to 255 separated by periods For Example 19202128 IPv6 address is 128-bit expressed as hexadecimal and separated by colons
• For Example 2001:db8:85a3:0:0:8a2e:870:7334
• IPv4 and IPv6 have reserved address for private networks. This is called as private addressing.
• Both IP networks can be divided into subnets or small groups.
• IP addresses that are permanently assigned are called as static IP address whereas if it is assigned newly at the time of booting then it is called as dynamic IP address.

    2. World Wide Web

 Introduction to World Wide Web (WWW) and its solutions

• World Wide Web (WwW) was invented by Tim Berners-Lee, a British scientist at CERN in 1989.
• It was originally invented to meet the demands of automatic information sharing and exchange of ideas between scientists, education intuitions and universities around the world.
• World Wide Web or simply Web should not be confused with Internet.
• It is system where documents and other online resources are interlinked with hyperlinks, identified using Uniform Resource Locator (URL) and accessed via the Internet.
• The user can use client side software called Browser to view information, images and multimedia objects displayed on the web pages.
• Hyperlinks enable the users to navigate between web pages.

    3. Uniform Resource Locator

Uniform Resource Locator

• Uniform Resource Locator abbreviated as URL specifies the address of an online resource and the mechanism to retrieve it.
• The format of the URL is similar to Unix file path syntax, where the forward slashes separate folder from files or other online resource names.
• Example http://www.facebook.com/techsmart.publication

Every URL consists of following parts

• The scheme name i.e. Protocol followed by a colon which defines namespace, purpose and syntax of the remaining part. Example ftp, http, and file URL schemes
• Domain Name corresponding to unique IP address pointing to destination location 
• Port number is optional and if omitted the scheme default is used.

• Complete Path of the online resource requested. It could be case-sensitive in case of non-windows based servers
• A query string containing data to be passed to software running on the server. It may contain name/value pairs separated by &Example first_name=web &last_name=programming 
• An optional string to specify a part or a position within the document or resource requested 
• A resource may contain references to other resources, in such cases relative.links are used to define the location of the second resource. Relative URL are dependent on the parent URL which contains a hierarchical structure used as reference in the relative link.

Hyperlink

• A hyperlink, or link, is a reference to data provided to the user by clicking tapping or hovering on the hypertext.
• Hyperlink may be used for pointing and navigating to a new document or specific location or point to an element within the document.
• Hypertext is the text that is linked and may be also called as anchor text Source document contains hyperlinks that allow the user to navigate and browse through web pages.
• Hyper links are often used to implement reference to definition in terms, index or glossaries.

Hope this post  is most helpful  for you thank you.