Question:
An OSPF router has three directly connected networks; 172.16.0.0/16, 172.16.1.0/16, and 172.16.2.0/16. 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 172.16.1.0 255.255.255.0 area 0
- router(config-router)# network 172.16.1.0 0.0.0.0 area 0
Explanation: To advertise only the 172.16.1.0/16 network the wildcard mask used in the network command must match the first 16-bits exactly. To match bits exactly, a wildcard mask uses a binary zero. This means that the first 16-bits of the wildcard mask must be zero. The low order 16-bits can all be set to 1.
Exam with this question: CCNA 3 v7 Modules 1 – 2 Exam Answers
Kecman replied 11 months ago
I just did a test and your answer, according to cisco test, is not correct.
Even it is logically correct by my all studies.
I got 96% because of that.
For the rest of you.
According to the cisco test, true answer is:
“router(config-router)# network 172.16.1.0 255.255.255.0 area 0”
But we all know that is not true answer.
If you want 100% answer this.
P30 replied 12 months ago
This answer is correct “router(config-router)# network 172.16.1.0 0.0.255.255 area 0” because /16 = 255.255.0.0 => wildcard mask is 255.255.255.255 – 255.255.0.0 = 0.0.255.255
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This answer is correct “router(config-router)# network 172.16.1.0 0.0.255.255 area 0” because /16 = 255.255.0.0 => wildcard mask is 255.255.255.255 – 255.255.0.0 = 0.0.255.255
I just did a test and your answer, according to cisco test, is not correct.
Even it is logically correct by my all studies.
I got 96% because of that.
For the rest of you.
According to the cisco test, true answer is:
“router(config-router)# network 172.16.1.0 255.255.255.0 area 0”
But we all know that is not true answer.
If you want 100% answer this.