HOSTNAME doesn't display in Traffic Graph

[xerxes]

My installation doesn't show up hostname in the traffic graph (LAN). How to solve this? I just upgraded to 2.1. Thanks.

[phil.davis]

It has to be able to do a reverse-looup of the IP address to hostname. For hosts with DHCP leases, you can select for them to be registered in the DNS Forwarder - "Register DHCP leases in DNS forwarder" and "Register DHCP static mappings in DNS forwarder".
For other hosts (like servers on the LAN that have a static IP), if their name-to-address and address-to-name are stored in a DSN server somewhere then;
Add a domain override to send the reverse-lookup requests to  that DNS server, like rows 3 and 4 in the attached screenshot. (rows 1 and 2 are sending real domains like abc.mydomain.com and xyz.abc.mydomain.com)
For other unknown IPs, you can add a Host Overrides entry specifying the name and IP. Then the DNS Forwarder can do both forward and reverse lookup on that data.