IP Changes

Developers, We are using Google reCaptcha in our website. We have firewall rules on our portal. We having issues with IP changes from Google recent days. Google keep on changing the IP's? How we can track IP Changes? Please advise me Thanks Kris -- You received this message because you are subscribed to the Google Groups "reCAPTCHA" group. To unsubscribe from this group and stop receiving emails from it, send an email to recaptcha+unsubscribe@googlegroups.com. To post to this group, send email to recaptcha@googlegroups.com. Visit this group at http://bit.ly/1dkFnYd. For more options, visit http://bit.ly/P65DvS.