Does Domain Parameters in ECDSA are same?

Question

In ECDSA,
Signer and Verifier should have same a, b and G?
such that y^2 = x^3 + ax + b, G is starting point.

Answer 1

Yes, the signer and verifier of an ECDSA message must agree on the curve parameters ahead of time. Several curves are named and defined in SEC2.