Hi,
Sometimes You can get ” ORA-12225: TNS:destination host unreachable ” error.
Details of error are as follows.
ORA-12225: TNS:destination host unreachable
Cause: Contact can not be made with remote party.
Action: Make sure the network driver is functioning and the network is up.
If the Network driver is broken and network is down, you can get this error. So you need to make sure network is up and enabled.
Sometimes you can get this error because of Firewall issues.
Or If database server is down, you can also get ORA-12225: TNS:destination host unreachable error.
Do you want to learn Oracle Database for Beginners, then read the following articles.
https://ittutorial.org/oracle-database-19c-tutorials-for-beginners/