function "gethostbyname" - how can i deactivate cache / force look-up???

Hi there - in a script I use the function "gethostbyname" to resolve a hostname (www.example.com) into an IP-address. Unfortunately, the host name that I try to resolve changes its IP address frequently. Since the function "gethostbyname" caches its results, it sooner or later returns a wrong IP-address. How can I deactivate cache for this function (or force the look-up) or what other function could I use to get the IP-address? Thanks a lot for your help in advance!!! Tobes =)