[qilo]

There's a registry key

  HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows NT\DNSClient\AppendToMultiLabelName
  [default value - 0 (Do not Append Suffix)]

which resolver built into Windows (DNS Client) respects.

nslookup contains its own DNS resolver and does not rely on the resolver built into the operating system. The DNS (multi-label) query packets sent by the nslookup tool will append the domains listed in the suffix search order (or primary DNS suffix if the list is empty) irrespective of that registry key.

In summary, don't use nslookup to try to get insight into what actually happens when apps/services try to resolve names. ping is probably a better bet, at least it uses Windows resolver which honours the above registry key.