The service on the Internet that does not require entering an account and password is DNS; DNS is a service of the Internet. As a distributed database that maps domain names and IP addresses to each other, it can make it easier for people to access the Internet. .
The operating environment of this article: Windows 7 system, Dell G3 computer.
What are the services on the Internet that do not require entering an account number and password?
In the Internet, a service that does not require users to set up accounts and passwords is DNS - Domain Name System.
The Domain Name System (English: 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 access the Internet more conveniently. DNS uses UDP port 53. Currently, the limit on the length of each level of domain name is 63 characters, and the total length of the domain name cannot exceed 253 characters.
is responsible for translating FQDN (that is, names ending with "." separated) into an IP. The initial DNS system used a huge hosts.txt file, but after a while, development had to use a database to replace the hosts.txt file, and eventually developed into the current distributed database.
The DNS system is a huge tree, with an unnamed root at the top, and the next level is arpa, com, edu, gov, int, mil, us, cn. Wait, arpa is the top of the domain name anti-parse tree; domain names such as com, edu, etc. were originally only used in the United States (this is a technical privilege).
But now it is used almost all over the world; and us, cn, etc. are called national domains. The domain names in this tree are not managed uniformly. The Network Information Center (NIS) is responsible for allocating top-level domains and delegating other authoritative agencies in the area.
There are two ways of mapping host name to IP address:
1) Static mapping, the mapping of host to IP address is configured on each device , each device independently maintains its own mapping table, and is only used by this device;
2) Dynamic mapping, establish a domain name resolution system (DNS), and only configure the host to IP address on a dedicated DNS server For mapping, devices on the network that need to communicate using host names first need to query the DNS server for 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.
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