For some reason TNSPING totally works as expected besides one annoying aspect. After returning a result like "OK (20ms)" it hangs for about 5 minutes.
Here's my environment: Windows 7 64bit client, Oracle 12.1.0.2 64bit client.
It doesn't matter which DB I ping, even if I provide a not existing database name it returns an error quite immediately and hangs after that.
I've recorded a trace file already by adding TNSPING.TRACE_LEVEL = SUPPORT to SQLNET.ORA but it only contains entries till the result is shown. While it hangs nothing is logged.
Connecting to databases using sqlplus or e.g. TOAD is not a problem either.
similar issue was resoved by removing LDAP from sqlnet.ora see here: https://sqljana.wordpress.com/2015/04/13/sqlplus-tnsping-everything-just-hang-without-errors/