When configuring OSPF on the ERX， what is the default auto-cost reference-bandwidth value？（）

单项选择题Whywouldyoumakeanon-backboneareaastubornot-so-stubbyarea？（）

A. to aggregate routes learned from the ABR
B. to lower the cost of routes advertised by the ABR
C. to connect a non-contiguous area to the backbone
D. to decrease the size of the link-state database in that area

单项选择题DuringOSPFadjacencyformation，whatstateisarouterinwhenitissendingLSAheaderinformationtoitsneighbor？（）

A. Init
B. 2Way
C. ExStart
D. Exchange

单项选择题WhichstatementistrueaboutthefrequencyofOSPFLSAtransmissions？（）

A. They are configured per OSPF area.
B. They are configured per virtual router.
C. They are configured per OSPF process.
D. They are configured per OSPF interface.

单项选择题Whattypeofroutercannotexistwithinastubarea？（）

A. ABR
B. ASBR
C. internal router
D. non-backbone router

单项选择题IfallOSPFroutersonabroadcastnetworkhavethesameOSPFpriority，whatparameterisusedtodeterminethenewBDRatthetimeofaDRfailure？（）

A. area ID
B. router ID
C. loopback address
D. IP address of interface on broadcast network