Do most corporate firewalls do deep packet inspection? I think that they'd mostly just be blocking domains based on a blacklist, or with a regex. Since most st

Do most corporate firewalls do deep packet inspection? I think that they'd mostly just be blocking domains based on a blacklist, or with a regex. Since most startups would be using a subdomain of their own domain for their tumblr blog, so I don't think this is an issue.