Which two statements are correct about OSPF in a multiarea environment? (Choose two.)

A.
OSPF will by default summarize routing updates between areas.

B.
OSPF requires the use of the area range configuration command only when nondefault summarization is required.

C.
OSPF ABR routers are needed only at the boundary of another OSPF area.

D.
OSPF uses wildcard masks in the network statements but subnet masks in the area range statements.

E.
OSPF requires that all areas have a least one ASBR.