The Domain Name SystemA name that identifies one or more IP addresses. For example, the domain name microsoft.com represents about a dozen IP addresses. Domain names are used in URLs to identify particular web pages. For example, in the URL http://www.hotmail.com/, the domain name is hotmail.com. Each domain name has a suffix that indicates which top-level domain (TLD) it belongs to. There are only a limited number of these domains. For example: · government – ​​Government agencies · edu – Educational institutions · org – Organizations (non-profit) · mil – Military · com – commercial enterprises · net – Network organizations ca – Canada · th – Thailand Because The Internet is based on IP addresses, not domain names; each web server requires a Domain Name System server to translate domain names into IP addresses. Internet protocol addresses are a 32-bit integer. If someone wants to send a message, it is necessary to include the destination address, but people prefer to give machines names that are pronounceable and easy to remember (hostnames). This is why the Domain Name System is used. These logical names also make it possible to not know the physical location of a host. A host can be moved to another network, while users continue to use the same logical name. The Domain Name System (DNS) is a distributed database used by TCP/IP applications to map host names and IP addresses and to provide email routing information. Each site (e.g., university department, campus, company, or department within a company) maintains its own database of information and runs a server program that other systems on the Internet can query. T...... middle of paper ......Lvalue in the response that specifies how long it guarantees the connection is maintained. DNS Formatting: When the user wants to send a message, they invoke an application program and provide the name of a machine with which the application should communicate. The application program must find the IP address of the machine. It passes the domain name to a local resolver (LR) and requests an IP address. The local resolver checks its cache and: If the LR has a response, it returns the response. If the LR does not have one, it sends the message to the server. The server then sends back a similar message containing the answer to the questions for which the server has bindings. If the server cannot respond, it sends responsive information to other servers that the client can contact. Describes a noun. Bibliography: