You may just block the IP addresses of these domains on firewall but that will create problems for other websites as well.
Such as, if you block youtube (google service) by IP, you are actually not blocking youtube but also blocking videos shared on other websites and blogs. You will also make problem partially to websites integrating google services such as analytics and adsense.
I recommend you to put a proxy for URL based blocking rather than over-burdening your firewall.
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Posted by WebUser Syed Asad Ali Rizvi from Cisco Support Community App
