IntermediatePhone
2 min
Subnet vs VLAN
NetworkingSubnettingL2/L3
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Interview Question
What is the difference between a subnet and a VLAN, and how do they relate in typical architectures?
Key Points to Cover
- Subnet is L3 IP range; VLAN is L2 broadcast domain separation
- Often 1:1 mapping but not required
- Routing happens between subnets; switching within VLANs
Evaluation Rubric
Explains subnets at Layer 334% weight
Explains VLANs at Layer 233% weight
Describes mapping and routing implications33% weight
Hints
- 💡Think: broadcast domain vs IP addressing.
Common Pitfalls to Avoid
- ⚠️Confusing Layer 2 (VLANs) and Layer 3 (Subnets) operations or their respective functions.
- ⚠️Stating that a one-to-one mapping between a subnet and a VLAN is always strictly required, rather than a common best practice.
- ⚠️Failing to explain *why* they are used together and how they complement each other in network design.
- ⚠️Not explicitly mentioning broadcast domains in the context of VLANs, which is a core concept.
- ⚠️Omitting the role of routers or Layer 3 switches in enabling communication *between* different subnets/VLANs.
Potential Follow-up Questions
- ❓What device routes between VLANs?
- ❓How do trunk ports work?
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