Listener protocol error - Oracle Okay first things first, this is probably a common issue which gets resolved going through all those questions and googling it but still I face this issue:

LSNRCTL&gt; service
Connecting to (ADDRESS=(PROTOCOL=tcp)(HOST=)(PORT=1521))
TNS-12541: TNS:no listener
 TNS-12560: TNS:protocol adapter error
   TNS-00511: No listener
   Linux Error: 111: Connection refused

When I tnsping my service name it works: 

$ tnsping TESTDB

TNS Ping Utility for Linux: Version 11.2.0.4.0

Copyright (c) 1997, 2013, Oracle.  All rights reserved.

Used parameter files:

Used TNSNAMES adapter to resolve the alias
Attempting to contact (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = FIHOST)(PORT = 1523))) (CONNECT_DATA = (SERVICE_NAME = TESTDB)))
OK (0 msec)

But not with: 

$ tnsping FIHOST

Used parameter files:

Used HOSTNAME adapter to resolve the alias
Attempting to contact (DESCRIPTION=(CONNECT_DATA=(SERVICE_NAME=))(ADDRESS=(PROTOCOL=TCP)(HOST=172.18.23.199)(PORT=1521)))
TNS-12541: TNS:no listener

AND 

$ tnsping FIHOST.level.com

Used parameter files:

Used HOSTNAME adapter to resolve the alias
Attempting to contact (DESCRIPTION=(CONNECT_DATA=(SERVICE_NAME=))(ADDRESS=(PROTOCOL=TCP)(HOST=172.18.23.199)(PORT=1521)))
TNS-12541: TNS:no listener

PS: FIHOST.level.com is registered in DNS

Listener.ora:

LISTENER_TESTDB =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = FIHOST.level.com)(PORT = 1653)

SID_LIST_LISTENER_TESTDB =
  (SID_LIST =
    (SID_DESC =
      (ORACLE_HOME = /u01/11.2.0.4/product)
      (SID_NAME = TESTDB)

Tnsnames.ora:

TESTDB =
  (DESCRIPTION =
   (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = FIHOST)(PORT = 1523))
    (CONNECT_DATA =
      (SERVICE_NAME = TESTDB)

Also, local_listener                       string      (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=FIHOST.filevel.com)(PORT=1653)))

There isn't sqlnet.ora configured.

Ideally, it should show which parameter file it uses and also it should be able to tnsping with hosts as well right? What could be the issue?

Thanks!
You can only tnsping to a database that is defined in your tnsnames.ora or OID. If I understand well then FIHOST is a server. To see if that is up you must use a common ping.