Let's says that someone told me that network address is 192.168.70.0, but he does not tell me the neither broadcast address nor network mask.
Is it correct to say that I cannot determine the maximum IP address in such a network, or should I say that 192.168.70.0 is the network address of a Class C network, so the maximum IP address is 192.168.70.254.
In other words, and perhaps the question is silly, what's the difference between a network and a subnetwork?
Network classes are dead, killed in 1993 by RFCs 1518 and 1519, which defined CIDR (Classless Inter-Domain Routing). Modern networking does not use network classes. When there were network classes, any network with a mask length longer than the class default mask length was a subnet of the network.
Since CIDR, a subnet is any network with a mask length longer than a network of which it is part. The term network can be applied to any subnet. Technically, any network is a subnet of 0.0.0.0/0. Today, the terms can usually be used interchangeably. You normally would use subnet when comparing to a larger network, or as a verb when chopping a network into smaller networks.
To answer your question, it is correct to say that the IP address range cannot be determined by the network number alone, such as 192.168.70.0. The subnet mask must be known. To answer the network vs subnetwork question, let's use the subnet you provided. If you have a network of 192.168.70.0/24 (/24 = 255.255.255.0), you can break that network into multiple SUBnetworks (aka subnetting) by simply changing the subnet mask.
