A subnet is technically a division of an network by range of ip address
A subnet is also known as:
In the internet age, all networks may be considered as subnet.
It is used to represent a subnet of hosts which can be reached over a network interface.
A SubNet is a partially qualified internet address in numeric (dotted quad) form, optionally followed by a slash and the netmask, specified as:
All hosts on a subnet have the same mask.
0.0.0.0/0
In a whois request, you can see the NetRange back (and the CIDR notation)
Example:
whois 172.70.250.60
NetRange: 172.64.0.0 - 172.71.255.255
CIDR: 172.64.0.0/13
A private subnet has no Internet access and can host the backend systems such as databases or application servers.
A public subnet send and receive traffic directly from the internet.
The maximum size of a network is given by the number of addresses that are possible with the remaining, least-significant bits below the mask prefix. See the mask table
You can bind a whole subnet on one machine. See subnet binding