Classless Inter-domain Routing (CIDR)

Classless Inter-Domain Routing (CIDR) is the successor to class-oriented domains for internet routing. The original IPv4 system would give Class A and B networks addresses that could handle between 65 thousand and 16 million hosts, but few organizations needed even a fraction of that many addresses. Organizations simply were not using that many computers on the internet. CIDR can assign addresses more precisely. One IP address can represent thousands of users of a single internet service provider (ISP).

What Small and Midsize Businesses Need to Know About Classless Inter-domain Routing (CIDR)

This system created three classes that contained a specific number of addresses. However, each class contained more addresses than SMBs could possibly use. The CIDR system is less wasteful because it doesn't force companies to claim more addresses than they need. With CIDR, routing is much simpler and more efficient. It doesn't require nearly the number of routing table entries. A large number of these entries can affect the performance of a router and eventually cause it to break down. CIDR is easier to use and potentially less expensive.

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