Cos'è un indirizzo IP
An IP address (Internet Protocol Address) is the unique numerical identifier assigned to each device within a TCP/IP network.
Il protocollo IPv4
IPv4 represents the historical standard, composed of 32-bit addresses usually written in dotted decimal notation (e.g., 192.168.1.1).
The structure of an IPv4 address is divided into a part dedicated to the network (Network ID) and a part for individual devices (Host ID).
IPv4 addresses were originally divided into classes (A, B, C, D, E), but this rigid system has been overcome in favor of CIDR.
L'avvento di IPv6
The exponential growth of connected devices has led to the depletion of IPv4 addresses, making IPv6 indispensable.
IPv6 uses 128-bit addresses written in hexadecimal form (e.g., 2001:0db8:85a3:0000:0000:8a2e:0370:7334), guaranteeing an almost infinite addressing space.
In addition to the astronomical number of IPs, IPv6 introduces improvements in native security with IPsec and node auto-configuration.
Il concetto di Subnetting
Subnetting is the engineering technique that allows dividing a single physical IP network into smaller, more manageable logical subnets.
This practice optimizes the use of available IP addresses, increases performance by reducing packet propagation, and improves security.
To identify where the network address ends and the host address begins, the Subnet Mask (subnet mask) is used.
The CIDR notation (Classless Inter-Domain Routing) expresses this mask by indicating the number of network bits with a slash (e.g., /24).
Esempio pratico di subnetting
Taking the network 192.168.1.0/24, if we decide to perform subnetting with a /26 mask, we will divide the network into 4 independent subnets.
Each resulting subnet will have 64 total addresses, of which 62 can be used concretely by devices (excluding network and broadcast).
Conclusioni
Correct planning of addressing and subnetting is crucial for the stability, scalability, and security of any corporate infrastructure.