An OSPF router has three directly connected networks; 172.16.0.0/24, 172.16.1.0/24, and 172.16.2.0/24. Which OSPF network command would advertise only the 172.16.1.0 network to neighbors?

An OSPF router has three directly connected networks; 172.16.0.0/24, 172.16.1.0/24, and 172.16.2.0/24. Which OSPF network command would advertise only the 172.16.1.0 network to neighbors?

• router(config-router)# network 172.16.1.0 0.0.255.255 area 0
• router(config-router)# network 172.16.0.0 0.0.15.255 area 0
• router(config-router)# network 172.16.1.0 0.0.0.255 area 0
• router(config-router)# network 172.16.1.0 0.0.0.0 area 0

Explanation: To advertise only the 172.16.1.0/24 network the wildcard mask used in the network command must match the first 24-bits exactly. To match bits exactly, a wildcard mask uses a binary zero. This means that the first 24-bits of the wildcard mask must be zero. The low order 8-bits can all be set to 1.

Exam with this question: CCNA 3 v7 Modules 1 – 2 Exam Answers