Syslog-ng how to get domain names instead of IP address

How can syslog-ng get the domain names instead of IP address that I received? I'm able to get those information but in IP address, I would like to get the DST/HOST to domain names instead of getting IP address.

http://imageshack.com/a/img33/685/4aui.png

Also I did enable use_dns, use_fqdn and keep_hostname but I'm still unable to get the domain name.

options {
    use_dns (yes);
    use_fqdn (yes);
    keep_hostname (yes);
};

Solution 1:

If you have these options set (as you should), then it means that there is no reverse dns lookup available for the incoming IP. In this case, you will need to manually add the hosts to your /etc/hosts file and ensure that your nsswitch.conf file is set to use:

hosts:          files dns