CompTIA Network+ Practice Test

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Enhance your CompTIA Network+ skills. Prepare with comprehensive questions and hints for a successful exam experience. Excel in network management and troubleshooting!

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What protocol was commonly used before 802.1Q trunking?

IEEE 802.3
Inter-Switch Link (ISL)
Spanning Tree Protocol (STP)
Point-to-Point Protocol (PPP)

The correct answer is: Inter-Switch Link (ISL)

The reason Inter-Switch Link (ISL) is the correct answer is that it was specifically developed by Cisco to encapsulate traffic between switches, allowing for the transmission of multiple VLANs over a single physical link before the standardization of IEEE 802.1Q trunking. ISL operates at the Data Link layer and allows switches to maintain VLAN information while forwarding frames, enabling effective VLAN tagging. In comparison, while IEEE 802.3 refers to the standard for wired Ethernet networks, it does not provide the necessary functionality for VLAN tagging and trunking. Spanning Tree Protocol (STP) is designed to prevent loops in switched networks but does not facilitate the VLAN tagging necessary for inter-switch communication. Point-to-Point Protocol (PPP) is primarily used for direct connections between two nodes, such as in dial-up or DSL connections, and does not have a role in VLAN management or trunking.