About
A subnet is technically a division of an network by range of ip address
A subnet is also known as:
- a net range (ie 172.64.0.0 - 172.71.255.255)
- or a CIDR (different notation - ie 172.64.0.0/13)
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.
Notation
A SubNet is a partially qualified internet address in numeric (dotted quad) form, optionally followed by a slash and the netmask, specified as:
- the number of significant bits. See Classless Inter-Domain Routing (CIDR)
All hosts on a subnet have the same mask.
Example
The world
0.0.0.0/0
How to find the net range of a IP
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
Type
Private
A private subnet has no Internet access and can host the backend systems such as databases or application servers.
Public
A public subnet send and receive traffic directly from the internet.
Management
Size
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
Partition
Bind
You can bind a whole subnet on one machine. See subnet binding