What is a "forward map" in dhcp?

[Timothy Murphy]

When my son tries to connect to our LAN with his Blackberry,
the request is first refused and then accepted.
Why is this?
-------------------------------
Jun 13 08:13:50 helen dhcpd: 
  DHCPDISCOVER from 00:23:7a:7e:a9:4d via eth1
Jun 13 08:13:50 helen dhcpd: 
  DHCPOFFER on 192.168.2.209 to 00:23:7a:7e:a9:4d (BLACKBERRY-4A9A) via eth1
Jun 13 08:13:51 helen dhcpd: 
  Unable to add forward map from BLACKBERRY-4A9A.gayleard.com
  to 192.168.2.209: not authorized
Jun 13 08:13:51 helen dhcpd: 
  DHCPREQUEST for 192.168.2.209 (192.168.2.2) from 00:23:7a:7e:a9:4d
  (BLACKBERRY-4A9A) via eth1
Jun 13 08:13:51 helen dhcpd: 
  DHCPACK on 192.168.2.209 to 00:23:7a:7e:a9:4d (BLACKBERRY-4A9A) via eth1
-------------------------------

Why does he require authorization (at first),
and how could I give it to him?

-- 
Timothy Murphy  
e-mail: gayleard /at/ eircom.net
tel: +353-86-2336090, +353-1-2842366
s-mail: School of Mathematics, Trinity College, Dublin 2, Ireland