An error "Enter valid hosts file entries for persistent hostnames" appears when defining hostnames using a combination of lowercase and uppercase letters in the Persistent hostname list. (4377074)

An error "Enter valid hosts file entries for persistent hostnames" appears when defining hostnames using a combination of lowercase and uppercase letters in the Persistent hostname list.

When defining hostnames using a combination of lowercase and uppercase letters in Log | Options | Name resolving | Persistent hostname list, an error below appears.

=> dns_hosts
Enter valid hosts file entries for persistent hostnames.

 

The persistent hostname list used in syslog-ng is written into the /opt/syslog-ng/etc/hosts file, which functions similarly to the /etc/hosts file.  This file is for syslog-ng's use.

The DNS is case insensitive, therefore from a technical perspective, uppercase hostnames have minimal added value.

It's recommended to use lowercase hostnames in the persistent hostname list to avoid validation errors.