What is the function of dns?

DNS is a distributed database on the World Wide Web that maps domain names and IP addresses to each other. It allows users to access the Internet more conveniently without having to remember IP strings that can be directly read by machines. The process of finally obtaining the IP address corresponding to the domain name through the domain name is called domain name resolution.

#What is the function of dns?

DNS domain name system (Domain Name System), its function is to resolve domain names into IP addresses, domain names and IP addresses are linked together for services, so there is no need to enter the IP address, instead access the website by entering the URL.

Each IP address can have a host name. The host name consists of one or more strings separated by decimal points. With the host name, don't memorize the IP address of each IP device by rote. Just remember the host name that is relatively intuitive and meaningful. This is what the DNS protocol does.

DNS function mapping

1. Static mapping. The mapping from host to IP address is configured on each device. Each device Maintain its own mapping table independently and only for use by this device.

2. Dynamic mapping, establish a domain name resolution system (DNS), and only configure the mapping from host to IP address on a dedicated DNS server. Devices on the network that need to use host names for communication must first go to DNS. The server queries the IP address corresponding to the host.

The process of finally obtaining the IP address corresponding to the host name through the host name is called domain name resolution (or host name resolution). When resolving a domain name, you can first use the static domain name resolution method. If the static domain name resolution fails, then use the dynamic domain name resolution method. Some commonly used domain names can be put into the static domain name resolution table, which can greatly improve the efficiency of domain name resolution.

Importance of DNS

1. From a technical perspective

DNS resolution is the actual addressing method for most applications on the Internet; the redevelopment of domain name technology The development and various applications based on domain name technology have enriched Internet applications and protocols.

2. From a resource perspective

Domain name is an identity mark on the Internet and a unique identification resource that cannot be repeated; the globalization of the Internet has made domain names a national strategic resource that identifies a country's sovereignty.

DNS query type

1. Query method is divided into

Recursive query: either a successful response or a failed query is made. response. Generally, the query between the client and the server is recursive, that is, when the client sends a request to the DNS server, if the DNS server itself cannot resolve it, it will send a query request to another DNS server, and then transfer the result to the client.

Iterative query: The server receives an iterative query and replies with a result. This result is not necessarily the mapping relationship between the target IP and the domain name, but can also be the address of other DNS servers (in order to further obtain the target IP).

2. Based on the query content,

forward query queries the IP address by domain name.

Reverse query queries the domain name by IP address.

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