单项选择题
A. P1R1 is the exi t point out of the area for P1R3.
B. P1R1 is a level - 1 only IS - IS router.
C. P1R1 has been configured with a nondefault IS - IS metric.
D. P1R3 is a level - 2 only IS - IS router.
E. P1R3has been configured with a nondefault IS - IS metric.
F. P1R3 routing ta ble should contain i L2 entries.