What is a DNS Cache?
A DNS cache (sometimes called a DNS resolver cache) is a temporary database, maintained by a computer's operating system.
A DNS cache contains records of all recent visits and attempted visits to Web sites and other Internet domains.
The Purpose of DNS Caches :
The Internet relies on the Domain Name System (DNS) to maintain an index of all public Web sites and their corresponding IP addresses.
Every time a user visits a Web site by its name, the user's Web browser initiates a request out to the Internet, but this request cannot be completed until the Web site name is converted into an IP address.
That conversion process (called : name resolution) is the job of DNS, and it takes time.
A DNS cache attempts to speed up the process by handling the name resolution before the request is sent out to the Internet.