What Is DNS Internet?

The Domain Name System (abbreviation: DNS) is a service of the Internet. As a distributed database that maps domain names and IP addresses to each other, it can make people more convenient to access the Internet. DNS uses TCP and UDP port 53. Currently, the limit for the length of each domain name is 63 characters, and the total length of a domain name cannot exceed 253 characters. The DNS protocol is used to translate domain names into IP addresses (IP addresses can also be translated into corresponding domain name addresses).

DNS is a hierarchically distributed database system that maps domain names and IP addresses to each other. The DNS system uses recursive query requests to respond to user queries and provides critical basic services for the operation of the Internet. At present, most firewalls and networks will open the DNS service. DNS packets will not be intercepted. Therefore, a hidden channel can be established based on the DNS protocol, so that it can smoothly pass through the firewall and transfer data between the client and the server. ^[1]

DNS defines two kinds of messages, one is a query message; the other is a response to a query message, which is called a response message. Whether it is a query message or a response message, there are 12-byte headers and query problems. ^[3]

DNS is a hierarchical database system that can map domain names and IP addresses to each other. It mainly includes the following three components:

(1) domain name space and resource record;

(2) a name server;

(3) Resolver. ^[4]

Billions of IoT devices will have 5G connectivity in the future, and DNS will create entirely new requirements for the discovery and addressing of these devices. The IETF has also started some key protocol developments, such as "DNS Service Discovery" represented by DNS-SD. DNS-SD allows all devices to multicast each other among peers to quickly discover local devices and services. In a smart home setting, for example, this would allow a light control switch to automatically control all fixtures without any human-machine configuration or management steps. Therefore, compared with traditional DNS methods, DNS-SD will be expanded more effectively in the future, which requires the implementation of centralized query servers and a large number of manual configuration functions. ^[2]