Unable to Resolve Server Name or Address (4)

Problem description

Multiple tasks have recently seen more Availability Alert caused by the inability to parse the server, but it is not a large area of Error, Probe and the operator is not centralized. Please help analyze the specific reasons.

Problem analysis

Exporting the recent error Probe, we found that the cities and operators have no common features and are relatively random, but most of them are located in the north.

2. Filter out the error Probe and reproduce it
Customer tasks can always be reproduced

Baidu and Taobao data are normal

Error Probe packet capture
It was found that the client has been parsing RequestDNS, but the DNS server has not returned.

Problem summary

Comparing the data, there is no problem with Probe

From the packet capture, the client has been sending DNSRequest. The DNS server did not respond, so an error was reported.

It is suspected that there is a problem with the DNS server policy. It is recommended to check the domain name resolution policy.

Unable to Resolve Server Name or Address (4)

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