I know /sbin/ifocnfig eth0 give you you IP
This si from this site http://proftpd.linux.co.uk/docs/faq/...h4.html#AEN352
The hosting machine has a poorly configured hostname setup to the point where the resolver library cannot determine the IP from the name. Solutions include, fixing the DNS for the domain, fixing the hostname, fixing the /etc/hosts file. Which one works for you will largely depend on your OS and exactly what is wrong.