What is an IP Address
An IP address (Internet Protocol Address) is a unique numerical identifier assigned to each device within a TCP/IP network.
The IPv4 Protocol
IPv4 represents the historical standard, consisting of 32-bit addresses typically 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IPv4 addresses were originally divided into classes (A, B, C, D, E), but this rigid system has been superseded in favor of CIDR.
The Advent of 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), ensuring an almost infinite addressing space.
In addition to the astronomical number of IPs, IPv6 introduces native security improvements with IPsec and auto-configuration of nodes.
The Concept of 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 (Classless Inter-Domain Routing) notation expresses this mask by indicating the number of network bits with a slash (e.g., /24).
Practical Example of 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, with 62 usable by devices (excluding network and broadcast).
Conclusion
Proper planning of addressing and subnetting is crucial for the stability, scalability, and security of any corporate infrastructure.