The correct answers are:
Subnet mask: 255.0.0.0
Network address: 125.0.0.0
Step-by-step explanation:
Given IP address: 125.34.13.2
First you need to find out what class that IP address belong to. Well, as you can see, the first octet has the value 125, which means that it belongs to Class A.
Now that we know the class, we can write its subnet Mask. As the given IP belongs to Class A, the subnet mask in that case will be 255.0.0.0.
Now that we have the subnet mask, we can easily find the Network address. The network address of IP, 125.34.13.2, with subnet mask, 255.0.0.0, will be 125.0.0.0. Just take the octet of the IP for which the octet of subnet mask is 255. In this case, the first octet of the subnet mask is 255, therefore, the first octet of IP will become the first octet of the network address, while the rest will become 0 as the rest of the octets of subnet mask are 0.