DNS is domain naming service and used to resolve host names to IP addresses and IP addresses to host names. The computer understands only numbers to communicate with each other. Its also easier way to make access websites by assigning names to websites.
When we use web address e.g. http://ittechjobs.net in browser, computer uses DNS for IP address to redirect the website.
Forward lookup: Converting names to IP address is called forward lookup.
Reverse lookup: Resolving IP address to names is called reverse lookup.
‘A’ record: It is called host record and it is used to map name to IP address. This is the record in DNS with the help of which DNS finds the host name.
‘MX’ Record: it is called mail exchanger record. It is the record needed to locate the mail servers in the network. This record is also found in DNS.