dig full name Domain Information Groper, it is a DNS domain name information query tool, and to see the domain name resolution process can be used.
dig is a tool that comes under linux, if you need to download and use the configuration in windows, the process is simple.
Csdn quoted a blogger's blog: Windows download configuration dig
Above, below how to input from the address bar https://www.cnblogs.com/jeavenwong procedure to find the ip address corresponding to the domain as an example, to remove the https protocol '' https: // "and user resources behind space "/ jeavenwong".
That is the ip address of www.cnblogs.com.
We know that, if the query did not hit ip when the host operating system and configuration files of level three cache cpu words, DNS resolution will grade recursive queries, roughly as follows:
Queries from the top-level domain root name server NS and A records (ip) -> query from a top-level domain to the secondary domain name server NS and A records (ip) -> from the secondary domain name server queries the host's ip address
The figure is a direct query results with dig:
ANSWER SECTION can be seen that there are two ip address, there are two host instructions www.cnblogs.com ip address.
The following shows the entire rules:
As can be seen from the figure the server is a top-level domain name server obtained from the root (.root) (.com) NS records, and secondary Domain Name Server (cnblogs.com) obtained from the TLD name server NS record, and then from cnblogs.com obtained two host servers and two NS record a (ip address).
dig can also query the NS records for each level, as shown below is the top-level domain NS record query, the query results from ip is 8.8.8.8 of the root name servers.
The figure is a secondary domain name query NS records.
Here is the query Host NS records.
I is limited, please leave a message if wrong correct me, thank you!