I have an existing Ubuntu 16.04LTS 64bit system that connects to Oracle 11g (184.108.40.206.0 64bit/Windows).
From that Linux machine I can connect to Oracle via sqlplus instantly, using
I just installed a Linux 18.04LTS, on which I installed the same oracle client and RPM header packages, prepared for 18.04 via
alien package converter:
oracle-instantclient12.2-basiclite 220.127.116.11.0-2 amd64 Oracle Instant Client Light package oracle-instantclient12.2-devel 18.104.22.168.0-2 amd64 Development headers for Instant Client. oracle-instantclient12.2-sqlplus 22.214.171.124.0-2 amd64 SQL*Plus for Instant Client.
Copied the same tnsnames, sqlnet and listener files, added same environment variables.
But. From the old machine the actual connection to the database in sqlplus takes about 0.5sec:
SQL*Plus: Release 126.96.36.199.0 Production on Tue Apr 16 16:17:13 2019 Copyright (c) 1982, 2016, Oracle. All rights reserved. [0,5sec] Connected to: Oracle Database 11g Release 188.8.131.52.0 - 64bit Production
And from the new one there is a pause of about 1 minute before displaying "Connected".
After connection is established, both sessions appear blazing fast when doing the queries.
I looked at the initial ideas regarding network and DNS resolution, but both machines are the same in this respect.
Is there anything Oracle serverside that could account for this?