recaptcha siteverify with Firewall

On the server on which we need to verify against  "http://bit.ly/11H4Jer", server is firewall protected. Can we use specific google server ip eg (216.58.217.132) rather than www.google.com for the firewall entry? So that only 1 google IP firewall rule is created. Is there any issue with method? -- 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.