windows DNS doesn't fall back to next server

spent all day with this issue at work. dns entries was 10.10.1.2 (ns2) and 10.10.1.1 (ns1)

windows apparently DOESNT fall down to the next server if it doesnt work. THANKS WINDOWS (':

flipping the dns entries (and a ipconfig /flushdns on one system) fixed it.

https://community.spiceworks.com/topic/292367-why-wouldn-t-a-computer-query-the-2nd-dns-server-if-the-primary-was-off-line

PS C:WindowsSystem32> nslookup ad ns1
Server:  ns1
Address:  10.10.1.1

Non-authoritative answer:
Name:    ad
Addresses:  10.10.2.104
          ...
          ...
          ...
          ...
          ...
          ...

PS C:WindowsSystem32> nslookup ad ns2
Server:  ns2
Address:  10.10.1.2

*** ns2. can't find ad: Server failed