Dear I'm Takeshi Suzuki. DNS Service was down. Why DNS Service was down? Event View logged this messages. named "..\rbtdb.c:1970: INSIST(!((void*)((node)->dnk.prev) != (void *)(-1))) failed, back trace" My Enviroment is below: OS:Windows2012 R2 Standard、BIND 9.10.4b2 x64 Sincerely