If you do a gethostbyname() and there is no trailing dot after a domainname that does not resolve, this domainname will ultimately be appended to the server-FQDN by nslookup.
So if you do a lookup for nonexistentdomainname.be your server may return the ip for nonexistentdomainname.be.yourhostname.com, which is the server-ip.
To avoid this behaviour, just add a trailing dot to the domainname; i.e. gethostbyname('nonexistentdomainname.be.')