Long DNS Time Analysis

Problem description

Configuration has completed the monitoring task. Why does the DNS Time display take so long? Analyze the reasons

Problem analysis

(1) From the analysis of the packet capture, the client sent DNSRequest for the first time. If the DNS server does not respond within 5 seconds, it will not be used and will send DNSRequest again.
From the customer's packet capture, the first DNSResponse Time returned data in more than 5 seconds, and the second response was within 5 seconds, so the time from the beginning to the second return of data was recorded.

There is a response within 5 seconds, but the time is not recorded because the DNS response packet exceeds the limit. The limit size is 512 bytes. The server sent 579, which exceeded the limit, so the data was not recorded.

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Solution

The server makes adjustments to reduce the size of DNS transmission packets.

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Problem description

Problem analysis

Solution