The working principles of DNS illustrate _dns server

Internet users with a certain technology base know what DNS is for, but most people are not sure how DNS looks for domain names. Ven found a picture that vividly describes the ripple effects of DNS lookups and may help people who do not know about DNS operations.

The following image comes from VeriSign, in order to simplify the process, the image ignores the effects of the cache (normally, the lookup results are often cached during different lookup periods):

Image source: Verisign Domain Name Industry Brief, June 2007 (PDF), last page

Find the ripple effect of www.example.com IP address:

The user's computer first queries the Domain name server (DNS server) used by the Web site. This process is a "recursive domain name server" in the picture.

The DNS server does not know the IP address of the www.example.com, so the DNS server starts a cascading query until it finds an IP address and reports to the computer (the IP address is consistent with the picture).

1. In the Internet root server to find, get the top-level domain name. com's DNS server.

2. Search for the top-level domain DNS server of the. com to obtain the example.com authoritative DNS server.

3. Locate the IP address of the host www.example.com in the exapmle.com authoritative DNS server, and finally return the IP address to the computer

4. It's done! Now the computer has obtained the www.example.com IP address, the user can visit this website.

For some, this is nothing new, but it has to be admitted that the image is indeed very vivid and worth sharing.