IP Addresses
An IP (Internet Protocol) address is a fundamental component of internet communication, used to pinpoint the geographical location of an address. In the realm of web operations services, IPv4 utilizes 32 bits for its addressing.
IPv5 and the Transition to IPv6
Contrary to its successors, IPv5 wasn't used for transmitting video data or streaming. Instead, it found its niche primarily within Apple's ecosystem, retaining the 32-bit structure. However, with the number of devices surpassing the (2^{32}) mark, the industry moved towards standardizing IPv6.
IP Address Classes
IP address classes, denoted by letters A, B, C, D, and E, delineate networks based on organizational size and purpose. Classes A, B, and C cater to different scales of network demands, while D is earmarked for multicasting and E is reserved for scientific endeavors.
Historical Context
During the Beginning stages of internet connectivity, access was confined to select organizations, setting the stage for the eventual expansion of network infrastructure.
Network Allocation and Classification
To maintain network integrity and separation, IP address ranges differ based on class classification. This classification is dictated by specific bit patterns:
Class A: 0 as the first bit
Class B: 10 as the first two bits
Class C: 110 as the first three bits
Class D: 1110 as the first four bits
Class E: 1111 as the first four bits
Calculating Possible Networks
Class A: (2^7) networks, excluding the 0th network.
Class B: (2^{14}) networks.
Class C: (2^{21}) networks, accounting for 3 reserved bits.
Each class has a specific range of addresses defined by the number of bits used for the network portion.
The remaining bits after network allocation determine the number of usable hosts per network.
Class A: Largest networks (fewest), most hosts per network.
Class B: Medium-sized networks, medium number of hosts.
Class C: Smallest networks (most numerous), fewest hosts per network.
Remember, the usable host range excludes the network address and broadcast address for each network.
| Class | Range | Network Bits | Usable Hosts per Network | Total Networks |
| A | 1.0.0.0 - 127.0.0.0 | 8 | 2^24 - 2 | 128 |
| B | 128.0.0.0 - 191.255.0.0 | 16 | 2^16 - 2 | 16,384 |
| C | 192.0.0.0 - 223.255.255.0 | 24 | 2^8 - 2 | 2,097,152 |
Information Needed:
IP address: The address assigned to a specific device on the network.
Subnet mask: A mask defining which bits in the IP address represent the network portion and which represent the host portion.
Steps:
Identify the Network Address:
Perform a bitwise AND operation between the IP address and the subnet mask. This operation retains only the bits that are "1" in both the address and the mask, effectively isolating the network portion.
The result of this operation represents the network address for the given IP address and subnet mask.
Identify the Broadcast Address:
Invert the subnet mask by replacing each "1" with a "0" and vice versa. This creates a mask with all host bits set to "1".
Perform a bitwise OR operation between the network address obtained in step 1 and the inverted subnet mask. This operation sets all host bits to "1", creating the broadcast address for the subnet.
Identify the First Usable Host Address:
Take the network address obtained in step 1.
Change the least significant host bit from "0" to "1". This sets the first host address within the subnet, excluding the network address itself.
| **Class | Network Bits | Host Bits | Subnet Mask | Example |
| A | 8 | 24 | 255.0.0.0 | 10.0.0.0 |
| B | 16 | 16 | 255.255.0.0 | 172.16.0.0 |
| C | 24 | 8 | 255.255.255.0 | 192.168.1.0 |
Example:
IP address: 192.168.1.10
Subnet mask: 255.255.255.0 (Class C network)
Network Address:
- 192.168.1.10 (IP) AND 255.255.255.0 (mask) = 192.168.1.0
Broadcast Address:
Inverted mask: 0.0.0.255
192.168.1.0 (network) OR 0.0.0.255 (inverted mask) = 192.168.1.255
First Usable Host:
- Change the least significant bit of 192.168.1.0 to 1: 192.168.1.2
Therefore, for the given IP address and subnet mask:
Network address: 192.168.1.0
Broadcast address: 192.168.1.255
First usable host: 192.168.1.2
A simple trick to quickly find the network and broadcast addresses of an IP address based on its class.
Determine the Class:
- Check the first few bits of the IP address to determine its class: A, B, C, D, or E.
Find the Broadcast Address:
For Class A, B, C, D, or E:
- Replace all bits after the first 8, 16, 24, 32, or 32 bits (depending on the class) with "1". This forms the broadcast address.
Find the Network Address:
- Replace all bits of the IP address with "0". This yields the network address.
Find the First Host:
Take the network address.
Change the least significant bit to "1". This gives you the first host address.
Example:
Let's take the IP address 192.168.1.10.
Class Determination:
- Since the first octet (192) falls within the range of Class C (192.0.0.0 to 223.255.255.255), this IP address belongs to Class C.
Broadcast Address:
For Class C, replace all bits after the first 24 bits with "1".
Broadcast Address: 192.168.1.255
Network Address:
Replace all bits of the IP address with "0".
Network Address: 192.168.1.0
First Host:
Take the network address (192.168.1.0).
Change the least significant bit to "1".
First Host: 192.168.1.1
Network Interface Card (NIC)
A NIC is a hardware component that enables your device to connect to a network. Understanding the logical structure of IP addresses within a specific subnet is essential for effective network management.