http://u.qdnx.org/file/bobjonkman-20140613T202653-z6c4mcn.html
#Best_Practices would say "Block everything, allow only what's necessary" implying that outbound ping should be blocked. In practice, I allow outbound ping. Philosophically, I'm in favour of an #OpenWeb, so I'm inclined to allow outbound everything. However, realities pervail (including $EMPLOYER policies), so I don't necessarily preach what I practice.