Which of the following IPv6 tunneling mechanisms support IPv6 IGP routing protocols?

Which of the following IPv6 tunneling mechanisms support IPv6 IGP routing protocols?
(Choose two.)

A.
Automatic 6to4

B.
Manually configured tunnel

C.
ISATAP

D.
GRE

Explanation:
The two point-to-point tunneling methods—manually configured tunnel
and GRE—support IPv6 IGPs. The two multipoint tunneling methods—automatic

6to4 and ISATAP—do not.