Overview
During recursion traffic analysis, the recursion module of the Private DNS service stays in a selected state in the analysis chart. The connection lines among the clients that initiate DNS requests in specified regions, the recursion module, and public authoritative DNS systems are blue.
The feature of recursion traffic analysis can analyze the recursive DNS requests that are sent to external networks. The main analysis items include the trend of the numbers of DNS requests, the latency trend, the numbers of requests in hotspot zones and hotspot subdomain names, the numbers of DNS requests from hotspot VPCs, and the numbers of DNS requests from hotspot client IP addresses.
Procedure
Log on to the Alibaba Cloud DNS console.
In the left-side navigation pane, click Private DNS (PrivateZone). On the page that appears, click Traffic Analysis Mode in the upper-right corner and click the Recursion Traffic tab.
Search criteria settings
You can set the following search criteria: time range, network scope, and the IP address of the desired client that initiates DNS requests.
Time range: You can specify a time range of up to 90 days. You can query the data within the last one year. The numbers of DNS requests within the last seven days can be displayed at minute level.
Network scope: Select the VPCs within your current account or within the account associated with your current account.
Client IP address: Enter the IP address of a client that initiates DNS requests. In most cases, enter the IP address of an Elastic Compute Service (ECS) instance. You can also enter the IP address of another Alibaba Cloud service instance.
Analysis reports of recursion traffic
Analysis of the numbers of recursive DNS requests
You can query the trend of the numbers of DNS requests that are initiated from a client IP address within a specific network scope by specifying a time range. You can also click the zoom icon in the upper-right corner to zoom in the chart. 
Analysis of the latency of recursive DNS requests
You can query the trend of the latency of DNS requests that are initiated by a client within a specific network scope by specifying a time range. You can also click the zoom icon in the upper-right corner to zoom in the chart.
Ranking of the numbers of recursive DNS requests
You can rank the numbers of DNS requests by Zone, Subdomain Name, Network, or Client IP Address by specifying a time range, a network scope, and a client IP address. The numbers of DNS requests can be ranked in descending or ascending order. The numbers of DNS requests are ranked in descending order by default. You can also click the zoom icon in the upper-right corner of each chart to zoom in the chart.
Ranking of the numbers of DNS requests for hotspot zones
Ranking of the numbers of DNS requests for hotspot subdomain names
You can enable cache retention for hotspot subdomain names. If you have activated the Private DNS service, the Add Cache Retention Domain Name dialog box appears when you perform this operation. If you have not activated the Private DNS service, you are redirected to the page for activating the service when you perform this operation. The Enable Cache Retention action is unavailable for the subdomain names that have cache retention enabled.
Ranking of the numbers of DNS requests for hotspot VPCs
Ranking of the numbers of DNS requests for hotspot client IP addresses
