Cisco DTP (Dynamic Trunking Protocol) Negotiation

Hi,

I have one question. So the trunk negotiation would works if the two switches belong to the same VTP domain. The switch will throw an error says “Unable to perform trunk negotiation on port Et0/1 because of VTP domain mismatch.” My understanding is VTP will work after a trunk link establishes. So if I want to do a trunk between two VTP domain, I have to do the trunk in a nonnegotiable way , correct? Since trunk is the prerequisite for VTP to work, why Cisco won’t allow DTP to work if the two switches are not in the same VTP domain? It’s kinda like which comes first, the chicken or the egg . Sorry my question is kinda like I try to find quarrel in a straw. I’m just confused why they design it this way , is there any reason for it?

Appreciate your help like always.

Helen