How To Fix GW664 - Host name is not known

SAP Error Message - Details

• Message type: E = Error

• Message class: GW - Message Texts for Gateway

• Message number: 664

• Message text: Host name is not known

Self-Explanatory Message

Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of messages in the SAP system have a message text, however this is frequently insufficient to comprehend or resolve the problem.

To make things easier, more detailed information is frequently added to describe the issue, how to fix it, and the necessary steps or configuration modifications.

Unfortunately, there isn't any extra information in this error notice.

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Smart SAP Assistant

• What is the cause and solution for SAP error message GW664 - Host name is not known ?

  The SAP error message GW664 "Host name is not known" typically indicates that the SAP system is unable to resolve the hostname of a server or service that it is trying to connect to. This can occur in various scenarios, such as when trying to connect to an external system, a database, or even when accessing services within the SAP landscape.
  Causes:
  
  DNS Issues: The hostname may not be correctly configured in the Domain Name System (DNS), or the DNS server may be unreachable.
  Incorrect Hostname: The hostname specified in the configuration may be incorrect or misspelled.
  Network Configuration: There may be network issues preventing the SAP system from reaching the DNS server or the target host.
  Hosts File: The hostname may not be listed in the local hosts file (e.g., /etc/hosts on Unix/Linux or C:\Windows\System32\drivers\etc\hosts on Windows).
  Firewall or Security Settings: Firewalls or security settings may be blocking access to the hostname.
  SAP Configuration: Incorrect settings in the SAP system configuration (e.g., RFC destination settings) can lead to this error.
  
  Solutions:
  
  Check Hostname: Verify that the hostname is correct and properly spelled in the configuration.
  DNS Configuration: Ensure that the DNS server is reachable and that the hostname can be resolved. You can use commands like nslookup or ping to test hostname resolution.
  Update Hosts File: If the hostname is not resolvable via DNS, consider adding an entry to the local hosts file with the correct IP address and hostname.
  Network Connectivity: Check network connectivity to ensure that there are no issues preventing access to the DNS server or the target host.
  Firewall Settings: Review firewall settings to ensure that they are not blocking access to the hostname.
  SAP Configuration: Review the SAP configuration settings, especially for RFC destinations, to ensure that they are set up correctly.
  Restart Services: Sometimes, restarting the SAP services or the application server can resolve transient issues.
  
  Related Information:
  
  SAP Notes: Check SAP Notes for any specific guidance or patches related to this error message.
  Logs: Review the SAP system logs (transaction SM21) and the developer traces (transaction ST22) for additional context or related errors.
  Network Tools: Use network diagnostic tools to troubleshoot connectivity issues, such as traceroute or telnet to check if the target host is reachable on the required port.
  
  If the issue persists after trying the above solutions, it may be beneficial to consult with your network administrator or SAP Basis team for further investigation.