Dear Daniel,
I met a strange questions
Within the company office computer, can almost at the same time to the preferred DNS server and alternate DNS server request,
System version WIN10 enterprise edition, DNS DHCP or manual will appear the above situation, refund the domain also can appear
The above phenomenon is found by wireshark caught,

In theory should be the preferred DNS server cannot parse the will to backup DNS server

Question:
1, what possible reason is the problem?
2. My demand is to use the preferred DNS, first preferred DNS not relief of will to secondary DNS


Thank you ~!