Domain name resolution process

If you want to see more detailed process, you can find the relevant rfc in the http://en.wikipedia.org/wiki/Domain_name_system

Many of my friends may not know much about the domain name resolution process. To tell the truth, I don't understand it either. I only know how to add and modify A records. Today, I will take this opportunity to study together, in this way, domain name operations will be easier in the future.

Step 1: The client initiates a domain name resolution request and sends the request to the Local Domain Name Server.

Step 2: when the local domain name server receives the request, it first queries the local cache. If this record item exists, the Local Domain Name Server Returns the query result directly.

Step 3: If this record is not found in the local cache, the Local Domain Name Server directly sends the request to the root domain name server, then, the root domain name server returns to the Local Domain Name Server

Address.

Step 4: the local server sends a request to the domain name server returned in the previous step, and then the server that accepts the request queries its own cache. If this record is not found, the address of the domain name server at the relevant level is returned.

Step 5: Repeat Step 4 until you find the correct record.

Step 6: The Local Domain Name Server saves the returned results to the cache for the next use and returns the results to the client.

Let's take an example to illustrate the process of domain name resolution. Assume that if our client wants to visit the site www.9byte.com, the Local Domain Name Server of this customer is dns.chinatel.com, and the root domain name server is

NS. INTER. NET, the domain name server of the website to be accessed is dns1.name.com. The domain name resolution process is as follows:

(1) the client sends a request to resolve the domain name www.9byte.com.

(2) After receiving the request, the Local Domain Name Server queries the local cache. If this record is not found, the Local Domain Name Server dns.chinatel.com returns the request to the Root Domain Name Server NS. INTER. NET sends a request to resolve the domain name www.9byte.com.

(3) After receiving the request, the Root Domain Name Server NS. INTER. NET queries the local record and returns the following results: 9byte.com NS dns1.name.com (indicating that the Domain Name Server in 9byte.com is dns1.name.com ).

Dns1.name.com, and return the result to the Domain Name Server dns.chinatel.com.

(4) After receiving a response from dns.chinatel.com, the domain name server sends a request to dns1.name.com to resolve the domain name www.9byte.com.

(5) After receiving the request, the Domain Name Server dns1.name.com queries the local records and finds the next record, for example, www.9byte.com A 211.120.3.12 (that is, the added A record) (This record indicates that the IP address of 9byte.com is 211.120.3.12) and returns the result to the Local Domain Name Server dns.chinatel.com.

(6) The Local Domain Name Server saves the returned results to the local cache and returns the results to the client.

The above is the whole process of domain name resolution.