* Description: Knowledge of domain name server [DNS]
* Compatiablity: RDBMS 11g, 12c
* Date: 04:02 PM EST, 05/13/2017

<1> Domain Name Server:
     |__ DNS is "domain name/IP" database. It maintain a directory of domain names and translate them to Internet Protocol (IP) addresses.
         The purpose is that internet user can remember a human readable website name instead of public IP of web server.
         Acorss the Internet, the domain name/IP info are gathered together and housed at the Central Registry known as internet root servers. 
         By Auguest 2014, there are 380 root servers in 13 groups. [10 in U.S., 1 in London, 1 in Stockhom and 1 in Japan]. 
         Your ISP, such as Verizon, usually provides the IP/domain translation service via local installed doamin name server CLIENT.
         After you register a new domain name or when you update the DNS servers on your domain name, it usually takes about 12-36 hours for the domain name servers 
         world-wide to be updated and able to access the information. This 36-hour period is referred to as propagation.

<2> Register a Doamin Name:
     |__ You can register a domain name through some third party company websites, such as GoDaddy, AWS. After register domain name, you can also rent a web hosting server
         through GoDaddy, no matter Linux or Windows OS, and upload all .html file to that web server for being visited.