Layer 3: Network Layer: Expands to many different nodes (IP) – The Internet is IP based. Isolates
traffic into broadcast domains. Protocols: IP, ICMP, IPSEC, IGMP, IGRP, IKE, ISAKMP, IPX. If the
exam asks which layer a protocol with “I” is, remember IP, IGMP, IGRP, IPSEC, IKE, ISAKMP, … are all
layer 3, all except IMAP which is layer 7.