> Server1> ftp Server1.test.com > ftp: Unknown Host Server1.test.com > A system error occured; error code found in errno > ftp> Do you have a similar problem with other services, or is FTP the only one with a problem? nslookup Server1.test.com telnet Server1.test.com I haven't found a way to get exactly the same error message from my FTP client, but "Unknown Host" suggests that the problem is in name resolution. man resolver I assume that "Server1.test.com" is hiding some useful information, so I can't tell why you're getting "Unknown Host", but I'd look at ("ls -l") files like the following. Bad permissions on these can cause "Unknown Host" errors. /etc/hosts (Here: -rwxr-xr-x) /etc/nsswitch.conf (Here: -rwxr-xr-x) /etc/resolv.conf (Here: -rw-r--r--) (I don't know why "x" permission would be needed on any of these, but it makes sense that everyone would need "r" permission.) If I change the permissions on /etc/hosts or /etc/resolv.conf to 600, then I can get an error message like the following: urtx> ftp alp-l ftp: Unknown Host alp-l Name does not resolve to supplied parameters; neither nodename nor servname were passed. For user "root", it's not a problem: urtx# ftp alp-l Connected to alp-l.antinode.info. [...] Perhaps bad content in these files could also cause problems like this. > [...] changed ip details [...] Did you change DNS details, too?