If you are using a hosts file, make sure it contains FQDNs and pay close attention to the order in which they appear.

Check the hosts file and adjust it if necessary:

The FQDN must come first, followed by any aliases.

/etc/hosts

10.0.0.1   server1.example.com    server1    application1

If an alias is listed before the FQDN, you may encounter error messages that are not immediately traceable to this cause.