352-001 · Question #793
You want to split an Ethernet domain in two. Which parameter must be unique in this design to keep the two domains separated?
The correct answer is D. VLAN ID. VLAN ID is the Layer 2 identifier that defines an Ethernet broadcast domain, so assigning different VLAN IDs to each domain is what keeps them logically separated.
Question
You want to split an Ethernet domain in two. Which parameter must be unique in this design to keep the two domains separated?
Options
- AVTP domain
- BVTP password
- CSTP type
- DVLAN ID
How the community answered
(44 responses)- A2% (1)
- B2% (1)
- C5% (2)
- D91% (40)
Why each option
VLAN ID is the Layer 2 identifier that defines an Ethernet broadcast domain, so assigning different VLAN IDs to each domain is what keeps them logically separated.
VTP domain controls the administrative scope of VLAN database propagation; if the same VLAN IDs exist in both domains, traffic can still cross between them on trunk links.
VTP password is an authentication mechanism to prevent unauthorized VTP updates; it does not restrict forwarding of data-plane traffic between domains.
STP type (PVST+, RSTP, MST) governs loop prevention and does not define or enforce broadcast domain boundaries between VLANs.
A VLAN ID is the 12-bit tag (802.1Q) that identifies a distinct broadcast domain on a switch. By assigning non-overlapping VLAN IDs to each Ethernet domain, a switch will never forward frames from one VLAN into the other, providing true Layer 2 isolation regardless of physical topology.
Concept tested: VLAN ID as Layer 2 broadcast domain separator
Source: https://www.cisco.com/c/en/us/support/docs/lan-switching/vlan/10023-3.html
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