Recursive query and iterative query of DNS

After studying for a while, I was confused for a while, and finally understood. The simplest way to understand it is as follows:

Recursion: The method between the client and DNS. The client entrusts its DNS to query the ip address.

Iteration: The method between DNS servers. After the client uses recursion to communicate with DNS, DNS will search for the client. There may be many ways to do this. The common method is to directly query the client by root. If no result is found, the client will perform the latest query. For example, first go to root to find. com, then find sina.com from. com, step by step.

Two real DNS query modes
There are two inquiry principles: Recursive and Interactive. The former is asked by the DNS proxy by Intera.
Ctive method, which is directly used for Interactive inquiry by the local machine. As shown in the preceding example, when we query the name
Both query modes are interactive.
Recursive (Recursive): the query mode from the DNS client to the DNS Server. This mode sends the query packets to be queried
Wait for the correct response with the correct name. In this way, only the returned packets are correctly responded or cannot be found.
Message.
Interactive: the query mode between DNS servers, which is sent by the Client or DNS Server.
Send packets out and ask, the response data is not necessarily the last correct name location, but it is not an error
Message, he returns to tell you the closest IP address location, and then goes to the nearest IP address to find the name to be resolved, repeated actions
Until the correct position is found.

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