ICMP is layer 3 protocol, not layer 4
I will bring that to Scott’s attention.
Good pick up
Thanks for the catch. I changed around the slide and words to call out that TCP and UDP are layer 4 but ICMP is "officially" layer 3 but people still debate this. My source here is Cisco documentation and CCNA forums where the debate flares up every so often. In the end, these three protocols are the three that appear in the Security Group or Network ACL dropdowns so I wanted to be sure people understood what they were.