IP Address is the most Important in IT , IP address gives the way where our ports and protocol know that , where and which address to connect. When we talk about IP Address, there are 2 types of IP Address
IPv4
IPv6
Difference Between IPv4 and IPv6
IPv4 and IPv6 are Internet Protocol versions used for addressing devices on a network. Here’s a crisp comparison:
| Feature | IPv4 | IPv6 |
| Address Format | 32-bit numeric (e.g., 192.168.1.1) | 128-bit alphanumeric (e.g., 2001:db8::1) |
| Address Space | ~4.3 billion addresses | Virtually unlimited (3.4×10³⁸ addresses) |
| Header Size | 20 bytes | 40 bytes |
| Configuration | Manual or DHCP | Auto-configuration (stateless address) |
| Security | Optional (IPsec support) | Built-in IPsec |
| Routing | Less efficient | More efficient (hierarchical addressing) |
| Broadcast | Supported | Replaced by multicast |
| Adoption | Widely used | Gradually being adopted |
Key Takeaway: IPv4 is nearing exhaustion, while IPv6 is the future of scalable and secure networking.
In IPv4, IP addresses are divided into classes based on the first few bits of the address. This classification helps allocate IP ranges for different purposes.
IPv4 Address Classes
| Class | Range | First Octet | Purpose | Subnet Mask |
| A | 0.0.0.0 - 127.255.255.255 | 0-127 | Large networks (e.g., ISPs, large orgs) | 255.0.0.0 (default) |
| B | 128.0.0.0 - 191.255.255.255 | 128-191 | Medium-sized networks | 255.255.0.0 |
| C | 192.0.0.0 - 223.255.255.255 | 192-223 | Small networks (e.g., small businesses) | 255.255.255.0 |
| D | 224.0.0.0 - 239.255.255.255 | 224-239 | Multicasting | Not used for subnetting |
| E | 240.0.0.0 - 255.255.255.255 | 240-255 | Experimental (reserved for future use) | Not used for subnetting |
Key Points
Class A: Supports up to ~16 million hosts per network.
Class B: Supports up to ~65,000 hosts per network.
Class C: Supports up to 254 hosts per network.
Class D: Used for multicasting, not for regular addressing.
Class E: Reserved for research and experimental purposes.
Most modern networks now use CIDR (Classless Inter-Domain Routing) instead of strict class-based addressing for flexibility and efficient address allocation.
If you notice Between Class A and Class B , there is on address left completely that is 127.0.0.0, this address is called as Loopback address aka localhost. So if you want to ping your system itslef, you use it
Thanks for reading it till here this is just to give you small ground as we move ahead in AWS we will be needing this details while creating VPC and Subnets