Page 196 - Web Applications (803) Class 11
P. 196

Ð ÐConsult the Trusted DNS Servers
                 If a recursive DNS server or servers can't find what they're looking for in their cache memory, they look elsewhere. The
                 query then moves up the authoritative DNS server chain. The search will go on until a nameserver for the domain is
                 found. These authoritative name servers are in charge of maintaining these records for their domain names.

              Ð ÐAccess the DNS record
                 To find the IP address for www.cbse.nic.in, we'll look up the address record on the authoritative name server. The
                 record for www.web.com is accessed by a recursive DNS server from the authoritative name servers. The record is
                 then saved in its local cache.

              Ð ÐThe last step in the DNS process.
                 The information is stored on the recursive DNS server, which returns the record to your computer. The record is then
                 saved in our computer's local cache. It obtains our IP address from the DNS record and sends it to our browser. The
                 website will be now be displayed on our web browser.
              The full lookup operation takes milliseconds to complete from start to finish. Let's break down the components that
              make up the lookup process for a better understanding.

                                                                   IP address is in my DNS local cache.
                            IP address is not in my DNS local cache.
                               Type www.cbse.nic.in
                                                                               Recursive DNS Server

                                                                   IP address is not in my DNS local cache

                            IP address is in my DNS local cache           Recursive name server will store the record
                                                                          information its DNS local cache obtained
                                                                          from the Authoritative DNS server
                                                                   IP address is located in my DNS

                                                                                Authoritative DNS Server







              Domain Registration Process

              A name is mapped to a static IP address using the Domain Name System (DNS). These are used by computers to
              communicate with one another using a unique name. When a computer requests a URL, the DNS converts the name
              into an IP address. When you register for a website, one of the first things you'll have to do is choose a domain name.
              Then you go to a domain registrar and register your domain name.
              Domain registrars register your domain name and connect you to the Internet by ensuring that it is added to a massive
              database of domain names mapped to specific IP addresses.
              The following is the sequence in which the process takes place:

              Ð ÐYou go to a registrar who is accredited.

              Ð ÐYou go to the registrar’s website to see if the domain name you want is available. For example, if you wanted to
                 build a website with the domain name ebay.com, you’d discover that someone else has already done it. Most
                 registrar services have an easy-to-use search interface that lets you see if the domain you desire is already taken
                 and suggests alternatives.

              Ð ÐOnce  you've  decided  on  a  name,  you  must  submit  it  to  ICANN(Internet  Corporation  for  Assigned  Names  and
                 Numbers) using the registrar's website.



                194     Touchpad Web Applications-XI
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