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Don Burleson Blog 







ORA-12543: TNS: destination host unreachable

Expert Oracle Database Tips by Donald BurlesonNovember 10, 2015


The error "ORA-12543: TNS: destination host unreachable" is most commonly found when there is there is a problem with network connectivity; however, there are a few other reasons for encountering the error.

 The Oracle docs note the following about ORA-12543:

ORA-12543: 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.

Common causes for the ORA-12543 error include:

  • Network driver not functioning
  • There is a problem resolving the host name given in the address parameter of the tnsnames entry
  • Network is down or experiencing other problems
  • Firewall issues
  • Database server is down

Also, see my notes on troubleshooting network errors in Oracle.

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