CCNA Practice Exam - OSPF Qn.1

Got this from the practice exam here..

1. You are configuring OSPF on a router with three interfaces with the IP addresses listed below. Which of the following network commands would include all three interfaces in the OSPF routing process in a single area? (Choose all that apply)

Ethernet0 - 192.168.1.2 255.255.255.0
Ethernet - 192.168.2.2 255.255.255.0
Serial1 - 172.16.3.2 255.255.255.252
[SIZE=-1]a. network 0.0.0.0 255.255.255.255 area 0 [/SIZE]
[SIZE=-1]b. network 192.168.0.0 0.0.255.255 area 0[/SIZE]
[SIZE=-1]c. network 255.255.255.255 0.0.0.0 area 0[/SIZE]
[SIZE=-1]d. network 192.168.1.2 0.0.0.0 area 0
network 192.168.2.2 0.0.0.0 area 0
network 172.16.3.2 0.0.0.0 area 0[/SIZE]

Why is b. not correct also?Pls explain? THnkas!!!

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Comments

networker050184

Because B would not match the serial link.

billscott92787

1. You are configuring OSPF on a router with three interfaces with the IP addresses listed below. Which of the following network commands would include all three interfaces in the OSPF routing process in a single area? (Choose all that apply)

Ethernet0 - 192.168.1.2 255.255.255.0
Ethernet - 192.168.2.2 255.255.255.0
Serial1 - 172.16.3.2 255.255.255.252
a. network 0.0.0.0 255.255.255.255 area 0
b. network 192.168.0.0 0.0.255.255 area 0
c. network 255.255.255.255 0.0.0.0 area 0
d. network 192.168.1.2 0.0.0.0 area 0
network 192.168.2.2 0.0.0.0 area 0
network 172.16.3.2 0.0.0.0 area 0

Well look at it this way. We have 192.168.1.2 Eth0 and 192.168.2.2 Ethernet and 172.16.3.2 Serial1 Interface

b. states network 192.168.0.0 0.0.255.255 area 0

This means that it is going to include 192.168.0.0 - 192.168.255.255 in the 0 area. So, we would not include the Serial1 interface which is 172.16.3.2

JavonR

How is option D a correct choice? That IP address and wildcard mask certainly don't include 172.16.3.2...[SIZE=-1]
[/SIZE]

drew2000

Answer D has three networks, so the combination of all 3 fits the bill.

Drew

blackninja

Unless I'm getting rusty the answer is also:

a. network 0.0.0.0 255.255.255.255 area 0

The wildcard mask 255.255.255.255 means it doesn't care about the 32 bits, so the statement matches all the ip addresses.

JavonR

drew2000 wrote: »

Answer D has three networks, so the combination of all 3 fits the bill.

Drew

Ahh woops, I thought those were the unmentioned e and f

drew2000

JavonR wrote: »

Ahh woops, I thought those were the unmentioned e and f .

Me too the first time through!

Drew

Dubuku57

Thanks everyone! (a) and (d) are the answers indeed. Think i hadnt read the question correctly.
Drew, Javon I made that mistake too! =S