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Understanding IP Addressing and Subnetting

Understanding IP Addressing and Subnetting Understanding IP Addressing and Subnetting

Understanding IP Addressing and Subnetting

by Linux Playground

What is an IP Address?

An Internet Protocol (IP) address is a unique numerical identifier assigned to each device connected to a network that uses the Internet Protocol for communication. Think of it as the digital equivalent of a home address, guiding data packets to their destination.

Types of IP Addresses

  • IPv4 (Internet Protocol version 4): Consists of 32 bits, divided into four octets. Commonly represented as dotted-decimal notation (e.g., 192.168.1.1). Supports approximately 4.3 billion unique addresses.
  • IPv6 (Internet Protocol version 6): Introduced to address IPv4 exhaustion. Consists of 128 bits, divided into eight groups of hexadecimal digits (e.g., 2001:0db8:85a3:0000:0000:8a2e:0370:7334). Supports a virtually unlimited number of unique addresses.

IP Address Classes

IPv4 addresses are categorized into classes to define the network portion and the host portion of the address:

Class Range Subnet Mask Suitable For
A 1.0.0.0 to 126.0.0.0 255.0.0.0 Large networks
B 128.0.0.0 to 191.255.0.0 255.255.0.0 Medium-sized networks
C 192.0.0.0 to 223.255.255.0 255.255.255.0 Small networks
D 224.0.0.0 to 239.255.255.255 N/A Multicast groups
E 240.0.0.0 to 255.255.255.255 N/A Experimental purposes

What is Subnetting?

Subnetting is the process of dividing a larger network into smaller, more manageable sub-networks or subnets. This practice enhances network performance and security.

Benefits of Subnetting

  • Improved Network Management: Smaller networks are easier to manage and troubleshoot.
  • Efficient IP Address Utilization: Prevents wastage of IP addresses by dividing networks based on actual needs.
  • Enhanced Security: Limits broadcast traffic, reducing the risk of network-wide attacks.

Subnet Masks

A subnet mask is used to identify the network and host portions of an IP address. It helps in determining which part of the address is used for network identification and which part is for device identification.

Common Subnet Masks

  • Class A Subnet Mask: 255.0.0.0
  • Class B Subnet Mask: 255.255.0.0
  • Class C Subnet Mask: 255.255.255.0

Calculating Subnets

To calculate subnets, one must understand the concept of borrowing bits from the host portion of the IP address to create subnetworks. For instance, in a Class C network (255.255.255.0), you can borrow bits from the last octet to create subnets:

Example:

  • Borrowing 2 bits from the last octet:
  • Subnet Mask: 255.255.255.192
  • Number of Subnets: 22 = 4
  • Number of Hosts per Subnet: 26 - 2 = 62

CIDR Notation

Classless Inter-Domain Routing (CIDR) is a method for allocating IP addresses and routing. CIDR notation is used to represent a subnet mask along with an IP address, simplifying the representation:

  • Example: 192.168.1.0/24
  • The "/24" indicates that the first 24 bits are used for the network portion.

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