Cisco CCNA (200-301)Network FundamentalsHard
A network administrator needs to design a network where a single broadcast domain spans multiple physical switches. However, devices within this broadcast domain must be logically separated into different groups that cannot communicate directly with each other without going through a router. Which networking concept allows for this logical segmentation on Layer 2 switches?
- ALink Aggregation
- BSubnetting
- CTrunking
- DVLANs
Show answer & explanationAnswer & explanation
Correct answer: D. VLANs
VLANs (Virtual Local Area Networks) allow a single physical switch (or multiple switches connected via trunks) to be logically segmented into multiple broadcast domains. Devices within the same VLAN can communicate at Layer 2, but devices in different VLANs require a Layer 3 device (router or Layer 3 switch) to communicate, thus achieving logical separation within a shared physical infrastructure.
Why the other options are wrong
- A. Link Aggregation (EtherChannel) bundles multiple physical links into one logical link for increased bandwidth and redundancy, not logical segmentation.
- B. Subnetting is a Layer 3 concept for dividing IP networks, not directly for Layer 2 logical segmentation across switches.
- C. Trunking carries multiple VLANs over a single physical link, enabling VLANs to span switches, but it's not the segmentation mechanism itself.
Virtual Local Area Network (VLAN)
A logical grouping of network devices that allows a single physical switch or a network of switches to be segmented into multiple broadcast domains, isolating traffic at Layer 2.
- Each VLAN is its own broadcast domain.
- Devices in different VLANs cannot communicate without a Layer 3 device (router/L3 switch).
- VLANs improve security, network performance, and administrative flexibility.
- Trunk links are used to carry traffic for multiple VLANs between switches or to routers.
Memory trick: VLANs Slice Switches, Subnets Slice IPs, Trunks Carry All, LAGs Bundle Links.