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March 19, 2024

CIDR Chart

March 19, 2024
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CIDR Chart, short for Classless Inter-Domain Routing Chart, is a tool used in networking to efficiently allocate and manage IP addresses. It provides a comprehensive overview of IP address blocks, their associated subnet masks, and the number of available hosts within each subnet. This chart serves as a valuable reference for network administrators and engineers, aiding in the design and configuration of complex IP networks.


CIDR Chart revolutionized the traditional hierarchical IP address allocation method used prior to its introduction. In the earlier system, IP addresses were divided into fixed classes – Class A, Class B, and Class C – based on the number of network and host bits. However, with the rapid growth of the internet and increased demand for IP addresses, the limited address space provided by these classes became a hindrance.

CIDR, introduced in the 1990s, eliminated this limitation by allowing for a flexible allocation scheme. It employs variable-length subnet masks (VLSM), which enable networks to be divided into smaller subnets with different size requirements. With CIDR, network administrators have the ability to allocate IP addresses in a more efficient and granular manner, resulting in better utilization of the available address space.


The CIDR Chart offers several notable advantages over the earlier class-based addressing system. Firstly, it allows for the efficient allocation of IP addresses, ensuring optimal utilization and minimizing wastage. By enabling the division of large network blocks into smaller subnets, CIDR allows organizations to allocate IP addresses based on their specific needs. This flexibility leads to a significant reduction in address space exhaustion.

Moreover, CIDR provides improved routing efficiency by reducing the size of routing tables. Traditional class-based addressing required the advertisement of numerous individual routes, leading to a bloated and inefficient routing infrastructure. In contrast, CIDR enables route aggregation, where multiple IP addresses can be summarized as a single route. This aggregation reduces the complexity of routing tables, leading to faster routing decisions and improved network performance.


The CIDR Chart finds applications in a variety of networking scenariOS . From large enterprises to small businesses, any organization that relies on IP-based networks benefits from the efficient address allocation and routing capabilities provided by CIDR.

Network architects and administrators utilize CIDR when designing and implementing complex network infrastructures. They can segment IP address space into smaller subnets, classifying them based on usage, location, or other criteria. CIDR provides the framework for assigning IP addresses in a structured and organized manner, facilitating network scalability and management.

For internet service providers (ISPs), CIDR is indispensable in managing IP address assignments and routing across their networks. By implementing CIDR, ISPs can optimize the utilization of their address space and minimize the routing overhead, enhancing the overall stability and efficiency of their networks.


In the ever-evolving landscape of networking, CIDR Chart stands as a crucial tool for efficient IP address allocation and management. With its ability to flexibly divide IP address blocks and perform route aggregation, CIDR enables organizations to overcome the limitations of the traditional class-based addressing system. By providing network administrators with granular control and improved routing efficiency, CIDR helps create scalable, robust, and high-performing networks. Its significance in today’s digital world cannot be overstated and reinforces its status as a fundamental component in the realm of information technology.

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