In order to *www. facebook .comAs an example
Host name (WWW. /mail. /member. /space.)
Domain name (.facebook /.net /.cn /.org /.com)
Domain name reclassification
Cn is a top-level domain name, indicating China.
Com is a secondary domain name, indicating commercial organization.
Bilibili is a level 3 domain name, usually using your own name.
All domain names are managed by the root, which consists of a cluster of servers using just 13 different domain names, which are operated by 12 independent organizations.
Root DNS server
Top-level domain name server. Com /.cn/.net/.gov
Authoritative domain name server.bilibili/.qq /.baidu
The DNS domain name resolver is available on every computer. If it is incorrectly configured, you will find that the software works but cannot browse the Web because it usually uses IP addresses to access the server. The DNS parser sends requests to the server closest to it, which is the local server. Local servers are generally managed by ISPs, such as China Telecom and China Unicom. The local server checks its cache after receiving the authoritative message, and returns the message directly with the non-authoritative message. Local DNS server. Procedure (Recursion) In other cases, we take an iterative approach.
