Users Can't connect after DNS change
Today I have faced something really weird.
In the previous day, DNS admin, change the DNS record of one of the instance I take care of, and remove reverse resolution.
then, when users tried to connect to the instance, ORA-12545 was the unique answer the got from their client connection.
I reviewed tnsnames.ora and in there the only string about the host was the IP address.
And I check locally at the oracle server, and the instance and listener are working. And no change has been issued at oracle level.
I check server ping, tracert, remote desktop, everything fine, the oracle instance runs in a windows box.
Fortunately I have access to DNS server as well, and since that was the sole thing thas was changed, I restore as it was before the change, reoad dns, and check connection, after that the users can connect again.
so, the questions are:
Oracle Client Software stores some where kind of resolution for host besides tnsnames.ora?
Oracle client Software use reverse resolution with name or ip in someway?
Since, the DNS record was changed, there must be a adjust in localhost even IP addressing was used?
Even the issue has been solved, I really want to hear your opinions.
Thanks for reading.