What is native vlan and why?

- By default, it's vlan 1. You can change the native vlan, but never default vlan!

- Used for untagged traffic. i.e. CDP, VTP, STP, or mgmt traffic

- Used for VoIP

- Native vlan has to be the same on both switches. In another word, native vlan is per trunk per switch. 

What is vlan and why?

- A vlan is a subnet; a vlan is a broadcast 

- Flexibility and security