Will Netscape allow PHP to set a cookie with only an IP address?

I'm working on an improvement to a new web site and have it hosted on a server with only an IP. When I try to set a cookie in IE, it works, but when I try it Netscape, it fails.

Here's the code I'm using:

$randval=rand();
setcookie ("cookie1",$randval,time()+36000,"/",".2x.1xx.9x.2xx",0);