Yuck! Instr() will give you false positives on partials. F.E. you will find '1' in '1','10','101', etc.

I think you are taking a bad approach. Look at some of the subnet UDFs or read up on it in the FAQ.

Alternately, put all the octets into an array and use ASCan() which does not return partials.
_________________________
Give a man a fish and he will be back for more. Slap him with a fish and he will go away forever.