IP address of the websites is very difficult to remember, we want to visit again and again. But, we can remember the websites with their domain names, URLs. The DNS keeps a track of the IP addresses as well as the names.
A game of numbers and names
Domain Name Servers (DNS), distributed database, transform the machine names like www.abc.com to IP addresses like 199.254.100.8. When DNS maps the IP address to the machine name, then it is renowned as reverse mapping. When you search for the URL, www.abc.com into the search engines, the browser looks for the IP address of the URL using a directory service and this service is DNS. So, your machine contacts a DNS server to seek the IP address of the searched URL. Then, this DNS server makes contact with other DNS servers of the Internet.
All about three letter codes
A DNS server runs the DNS software and one of the high popular softwares among them is BIND (Berkeley Internet Name Domain) DNS. The root of the system is called the top, refereed as '.'. Seven immediate sub domain nodes, come under the root, are 'com', 'org', 'gov', 'mil', 'net', 'edu', 'Int', etc.
Parts of DNS:
DNS is comprised of two components, one is Nameserver and other is Resolver.
Nameserver:
Only one Nameserver is found for a group of machines. Nameserver is responsible for searching the names. If on one Nameserver, the required information is not present, then it contacts to others to look out for the information. Nameservers are well acquainted with the process of contacting the root nameserver that also knows about every authoritative nameserver.
There are three types of nameservers:
•Primary nameserver
•Secondary nameserver: Designed to serve backup purposes
•Caching nameserver: Resolve name queries without maintaining any DNS database files.
Resolver:
Resolver works on the client's machine for initiating DNS lookups. Basically, Resolver is comprised of the list of nameservers to use.
