By default Artica writes the IP address in events and statiscics. If you enable this feature, Artica queries the DNS for client hostnames or fully qualified domain names (FQDN). If Artica fails to resolve FQDN the IP address will be displayed. This feature is avaliable in SP163+
Be Careful with this option, this can slow down the web interface response especially in slower dns.
Before enable this option, make sure that you set your local DNS in DNS section and in Proxy section.
1º On left menu expand the Your proxy section
2º Clink in Global Settings
3º On General Settings tab, enable the option Resolve Hostnames in Proxy logs