Advanced Networking Administrator Test Prep

Answer: C - ISL and 802.1q provide inter-switch VLAN communication in a switched LAN environment.

Key Takeaway: Inter-switch Link, or ISL, is a Cisco Systems proprietary protocol that maintains VLAN information for traffic flow between network devices. It is Cisco’s VLAN encapsulation method and is supported only on Cisco’s equipment. 802.1Q, also known as VLAN Tagging, is a networking standard that allows multiple bridged networks to transparently share the same physical network link without leakage of information between networks. It is commonly used to refer to the encapsulation protocol.