DNS setup in rhel

The DNS is a distributed system, meaning that only the 13 root servers contain the complete database of names and addresses. All other DNS servers are installed at lower levels of the hierarchy and maintain only certain pieces of the overall database.

Most lower level DNS servers are owned by businesses or Internet Service Providers (ISPs). For example, Google maintains various DNS servers around the world that manage the google.com, google.co.uk, and other domains. Your ISP also maintains DNS servers as part of your Internet connection setup.

DNS is based on the client/server network architecture. Your Web browser functions as a DNS client (also called a DNS resolver) and issues requests to your Internet provider's DNS servers when navigating between Web sites.

When a DNS server receives a request not in its database (such as a geographically distant or rarely visited Web site), it temporarily transforms from a server to a DNS client. The server automatically passes that request to another DNS server or up to the next higher level in the server hierarchy as needed. Eventually the request arrives at a server that has the matching name and IP address in its database (all the way to the root level if necessary), and the response flows back through the chain of DNS servers to your client.

Publicly available DNS tools can be used to search for information related to Internet domains. Professional network administrators use these same basic tools on business networks.