
AWS Certified Advanced Networking – Specialty (ANS-C01) Certification Guide
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You may have noticed in the previous section that the Whois
results for the IP address 8.8.8.8
showed that the IP belongs to a CIDR of 8.8.8.0/24
. If you’re new to networking and the art of subnetting, then this may look quite odd at first. What does the /24
mean in that context? This section will explore CIDR (often pronounced cider) notation and how it is used in the world today. Before doing so, you will learn more about classful networking. While this type of network classification is not used in the current day, it is a key foundational element to understanding why things have evolved into their current form. That being said, the first subsection will cover classful networking, and then the next subsection will dive into CIDR.
In 1981, a rudimentary system was put in place to classify network ranges and boundaries by examining the high-order bits (first three bits) of an IP address. In layperson’...