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It does not require a subnet mask.
If this is a default subnet mask, then it would be a class C subnet mask. If you are subnetting a network and this is not the default subnet mask, then it could be either a class A or class B.
The default subnet mask has a standard size. The custom subnet mask allows you to make subnets that are smaller or larger than the default.
2 given subnets
255.255.255.0
255.255.255.0
The default subnet mask would be 255.255.0.0 for a class B address.
if the ip address is 192.168.2.1 then the subnet mask should be 255.255.255.0
Subnet mask for the above is 255.0.0.0
By changing subnet mask..from 255.255.224.0 to 255.255.240.0 Number of subnetworks increase and the number of host in each subnetwork decreases
This is a network address
It depends on whether you are subnetting or not. If not, the default subnet mask would be 255.255.255.0