no reverse dns

[Robin Becker]

We have just moved offices and our freebsd machine has started complaining in 
the following terms

Oct 29 17:14:39 int kernel: arplookup ww.xx.yy.zz failed: host is not on local 
network

We have an external router connected as a dhcp server at 192.168.0.2 which 
apparently has external address ww.xx.yy.zz. I am using a fixed ip address ie

192.168.0.6

I have this in my rc.conf

defaultrouter="192.168.0.2"
hostname="int.myoffice.com"
ifconfig_em0="inet 192.168.0.6  netmask 255.255.255.0"


and have dns mapping int.myoffice.com --> ww.xx.yy.zz, but our ISP will not make 
the reverse mapping. I assume that we're trying to reverse lookup something and 
the lack of reverse dns is causing this issue.

What can I add to my rc.conf to stop this arplookup problem?
-- 
Robin Becker