How many fully established neighbour relationships exist on an Ethernet with five routers running OSPF as network type broadcast?

How many fully established neighbour relationships exist on an Ethernet with five routers running OSPF as network type broadcast?
A . 5
B. 6
C. 7
D. 10
E. 20

View Answer

Answer: C

Explanation:

Assuming routers R1-R5, R1 is elected DR, R2 BDR. Fully established neighborships only occur to DR and BDR, all other neighbors are in 2Way DR other state.

DR|BDRFull relationships:

R2-R1

R3-R1

R3-R2

R4-R1

R4-R2

R5-R1

R5-R2